Assassinating the Iranian Nuclear Scientist
Mohsen Fakhrizadeh was a known objective of Bibi Netanyahu, and the action was almost certainly done (arranged or directly implemented) by Israel's Mossad. This operation had been carefully planned and was executed brazenly. There had been rumors that Israel would strike at Iran's nuclear facilities before Trump left office; this seems to be the chosen method to get at them.
If I can read Bibi's mind correctly, this was an item on his bucket list and there's no better time to cross it off. (Tick, tick...he is surely going one of these days/months/years, though still not at this time.) Apart from that, he wants to provoke Iran, with the objective of creating enough tension that the US, under the Biden Administration, would never be able to get Iran back to the table to resume the agreement to limit Iran's nuclear program that Trump trashed.
Although Trump probably has some delusional thought that if war starts between Israel and Iran in the meantime he can declare an emergency and stay in power, what he thinks is almost irrelevant now. Except for the damage he can still do; this is a good example of his opportunity for mischief: he can easily aggravate this if he wants.
I think there is faulty logic in the whole thing here: killing the scientist no doubt sets back Iran's chances of rapid breakout to a weapon--something that Iran had been making a significant feint toward doing since the agreement was breached (by us). That might buy Biden a few months if things go really badly, but I don't see this contretemps as likely to cause any serious impediment for his policy, which is to get Iran back to voluntary limits on its nuclear program. Biden can simply state US policy against assassination of civilians (or even suspected terrorists without a "finding") and demur from any comment on the action itself.
If we try--for just a moment, please--to look at it from the Iranian point of view, though, this would suggest more reason for Iran to return to the table than to refuse it. They don't have to indicate whether the murder affects their program, they just need to show willingness to return to limited nuclear development, which would be the easiest course for them going forward. Especially if this setback is a real one, not merely in perception of their regime's prestige.
Iran will feel a need, though, to respond to this assassination in some form, for the sake of that perception, as they did when Trump bumped off Qassem Soleimani. Only better than they did last time, I can hear the Ayatollah telling his Revolutionary Guard. I expect to see a rocket or two lobbed at Israel from one of Iran's allied units closer to the front (in Lebanon, Syria, Gaza, etc.) Beyond that, Bibi better go back to quarantine--I'm sure someone on his staff will test positive, or a positive test otherwise arranged. That is probably easy as pie for a spy.
Republicans Destroying Their Chances
Most of the Republican Congressional corps (House + Senate) has remained on the sideline in the Trump "Reckless and Feckless" campaign. They stay out of the retreat/regroup action, implicitly supporting his bootless claim to retain the Presidency. Trump's claims are an impossible mess of imagined conspiracy and failed accusations of misconduct in the count, and they know it. I can sympathize with these Congressional Cowards' reluctance to drop fealty to the cratering predatory beast in the White House, at least until he is declawed when he loses control of the Seal of the Presidency. Even then, his fangs will be (figuratively) real enough.
The error they are making in this strategy of inertia and silence, though, is that it gives them a difficult set of challenges in creating a strong argument for Republican-leaning Georgians to turn out in the critical runoff test for control of the Senate.
First, many of their voters may conclude from the Presidential race fiasco that elections (including those, specifically, in Georgia) are untrustworthy; why bother? I'd say that might resonate particularly with Republican-leaners in the suburbs or cities. The Trump campaign has shown a great willingness to dispense with the legal votes of hundreds of thousands if they are from the wrong precincts.
Second, the current policy invalidates one of the most cogent arguments, one that Mitch McConnell would surely love to employ forcefully with the PAC money he can command to preserve their majority: That the Georgia runoff is the last, only chance to prevent total control of Washington by the (fill in slanderous labels) Democrats. Mitch has to wait for that one until it is clear to all that the future President is not Trump. We may think it is "as clear as an unmuddied lake" that Biden won and that all realize it, but that is not so. For whatever reason they are told or tell themselves, most Republicans Out There believe Trump's allegation about the attempted theft of the election, and more incredibly, many believe he will somehow still squeeze out a win.