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.
People kind of understand probabilities by themselves, but if you let the probability get anywhere near any other percentage, most peoples' brains segfault and fall over. So while people understand a 75% chance of winning a double coin flip, and understand that getting 75% of the votes would be a landslide victory, something funny happens and they can't tell which is which when you tell them there's a 75% chance someone will win an election.