Because like everything else you idiots who think everything is doctored have claimed, it isn't actually doctored and your explanations make zero sense. There is no fucking possible way a greenscreen Biden would have only part of his body - but not the whole thing - move in front of some of the microphones, unless you literally intentionally went out of your way to rotoscope out his hands to put the microphone behind them, and ONLY them. The secondary angle also confirms it's a matter of him walking into the boom mics.

Go ahead and believe it, idiot. I'm sure you also think a missile hit the Pentagon because "I ANALYZED THE PIXELS".