Meek should only drop out of Crist agrees to caucus with the Democrats.
Well, then you run the issue of how many Republican-leaning Crist Supporters does that kick over to Rubio? Rick Scott is out-polling Rubio, so it's fair to say there are plenty of Scott/Crist voters that might have problems voting for a defacto Democratic candidate.
It would also completely destroy the image the Crist campaign has been trying to create--the "Non-partisan, People before politics" slogan would be hard to sell if you're committed to caucus with a specific party that dropped it's nominee and endorsed you.