It's an effective advert if the purpose is to increase awareness of fire safety. We have some awful ones in the UK with partially burnt teddy bears and stuff. I think it's more leveraging popular imagery to deliver that message, rather than expressing LGBT support.

You can see on the right of the image there is another progress flag with text on it. I think it's safe to say this image is framed in a way to eliminate the context.

It's cut off where it says almost exactly that on the right

Less catchy and you'd need smaller letters, tho ...