It bothers me that if you assume

1 Biden's chance of winning is .75
2 Biden's chance of winning the election conditional on winning Florida is 1
3 Biden's chance of winning Florida is .5

It follows that

Trump's chance of winning conditional on winning Florida is .5

It's like Biden has to win 1 out of 2 coin flips where the 1st is Florida and the 2nd is everything else

If he loses Florida, that erases his advantage elsewhere

Of course outcomes in different states aren't statistically independent but the argument in the first tweet is valid

Also it may be that the assumptions are false, but I think they are plausible.

I should add, the effect of Trump winning Florida on your beliefs is twofold:

1 You should update so as to believe that it is more likely that Trump will win other states.

2 Trump is now ahead by 29 electoral votes, which Biden must make up.