To be clear, DeSantis doesn't have to do a complete 180 on his stance. Currently, he is more on the side of not providing Ukraine aid. If he changes his position to be more on the side of providing Ukraine aid, then this would resolve as a YES.
How do we know if he changes his stance sufficiently? Simple, we go by the concensus of the mainstream media such as NPR, CNN, Fox, MSNBC, Washington Post, The Times etc. If the majority of these reputable sources are saying that DeSantis is now mostly on the side of providing Ukraine with aid, then that is what I will base my decision on.
Can we tighten these markets to roughly "will there be a logical contradiction between these candidates' prior statements and their future statements"? Each of these candidates left a lot of room for interpretation about exactly how much they are against Ukraine aid.