As usual you have failed to understand either the president's words or the politics involved. trump broke precedent in his first day in office, filing for the 2020 election. The norm was to wait till after the next mid-term election to form a campaign. Now of course the goose honking chorus of journalists at the first presser just HAVE to ask this inappropriate question, and of course the president has to deal with it. If Biden gives the impression that he is NOT going to stand for reelection then he becomes an instant lame duck and his power is reduced, so he gave an answer that maintained his "hand", nothing more, nothing less.