It's listed as a strategy title on Steam. It's also listed as top down strategy on Wikipedia. It's clearly not turn based because it happens in real time. Sure, you can pause the game to make decisions, and you can do that in the single player portions of most other RTS games such as AI War. Is AI War turn based strategy because the game encourages you to pause occasionally? Furthermore, pausing is not necessary as you can play an entire run of FTL without needing to pause it at all.
Granted many RTS games are hybrids of other genres, FTL is also a space simulation with rogue like qualities, and that's what makes RTS so innovative because the people making them aren't afraid to experiment. I see many genres in which there's very little innovation or experimentation going on, hence the comment.