Have yall never played poker/thrown a dice/anything random? When he says libs can relax its because the ODDS of winning are in his favor, but they are still fucking odds. Trump can still roll a 6 and win. If trump wins a) if he predicted that biden would have won, you'd get angry. b) if he predicted trump would have won, thats a shitty prediction that has little basis in the data and even if he was right nobody would listen to a guy who guessed right by chance!!
Think that i win if a coin lands thrice on heads. It's a 12.5% chance i win. Would you bet for me? No. Would you be surprised if i win? Also no, i still had a chance.
The chances lie in the fact that many ppl will vote on a whim based on how they feel one particular day, and you cant know all the data or how reliable it is. He isnt covering his ass, he is acknowledging that he cannot know with utmost precision. Its not a political/emotional thing, its how math works.
Compound odds are what really throws people off. Most people can conceptualize the odds of something happening once. When you have to predict 15-20 different outcomes (basically the number of state races that are anywhere close to being competitive), which are all conditional on each other to a varying extent (correlated demographics), AND you have to apply some sort of "secret sauce" tilt factor to all of your data (because polls are all guesses/models themselves and you have to make a judgement on their accuracy), it gets much more complicated.