It's not just the bigotry, I think we all know that corporations could easily get past that. He's shown that his anti-LGBT agenda is absolutely the top priority, and is quickly turning into an anti-business agenda
And who wants to go to a convention somewhere that normal behavior could get you harassed by the police? Or that could limit your medical treatment if you were to have an emergency? If I were a woman (or gay, or trans, or even just not a "traditional" straight cis person), I would be scared to step foot in Florida even for a work conference.
Not to mention that trans people have no safe option for using public restrooms in Florida. They could get harassed or arrested for using the one that matches their birth sex (because they don't look like that sex anymore) and for using the one that matches their gender (because oh god penises).