The one situation in which I’ve heard senior-year AP scores mattering in admission: UK universities will often have offers to American students that include getting a certain score on a certain AP test. Wouldn’t surprise me if other foreign universities have similar requirements.
While true, a foreign university is not what the OP is discussing. And in any event, in the case of UK universities, if the applicant does not have the requisite AP scores at the time of application, then any offer made is a conditional one which will list the AP scores required. Unlike US universities where there is some wiggle room in terms of how bad grades need to decline before rescinding, in the UK, it’s cut and dry. If the conditional offer to Oxford is based on receiving 5’s in Calc BC, Chem, and Bio, and final results are 5’s in Calc BC, Chem, Micro, Psych, and a 4 in Bio, that kid better have a back-up plan because he’s not going to Oxford.