For the exact reason that so many democrats feel like "Florida is too red to flip", Republicans who feel like Florida is a safe red may feel safe voting for RFK.
If he pulls ~6% of the vote and Florida has another 77% turnout, that's 6% of 10,341,570, which is 620,494 RFK votes.
If that split is 60% Trump voters and 40% Harris voters, that means 372,296 votes Trump doesn't get.
Trump won the state in 2020 by 371,686 votes.