You’re missing the point. You need to compare the 70% to how many actually voted for him in farmland. If he got 70% of the vote in that demo he hasn’t lost any support.
I think that all the poll says if that 70% of rural farmers would vote the same...the others would vote differently I assume
Of those that said they would vote differently, it doesn’t say if the voted for Trump in 2016 and wouldn’t now or if they voted for the evil beast and would vote for Trump now