He should have said something different

I'd argue that acknowledging the LGBTQ+ community in the aftermath of the Pulse nightclub shooting was vital. It wasn't just a matter of upholding the law, it was a targeted hate crime against a specific community. By saying "we will protect LGBT," Trump recognized the specific group that was under attack. It's the same as when a racially motivated crime occurs, leaders don't just say "we will uphold the law," they specifically address the group that was targeted.