This is not about "choosing another program"; this is about conditional CSS selection, and is a common HTML coding practice for web content that has to be tweaked to run on multiple browser implementations.
Maybe it would be simpler to ask: given that Freda doesn't handle floating images, could it simply present them as non-floating images. In other words, could Freda's implementation of <img .../> simply ignore the float attribute? (What it's doing now is ignore the entire img tag.)