That's the usual reason; don't want to pay for it, so they drop it. It's also possible those two channels aren't popular enough for the money paid to get them.
But nothing was said on the message as to why.
I will say, that I have used both "TV Everywhere" (e.g. watching USA/SyFy/etc episodes the next day on my iPad remotely) and Netflix's "Super HD" -- things I wouldn't have guessed that Frontier would have gotten for its customers.
(However "TV Everywhere" is not entirely accurate -- for example, it doesn't work when one is traveling in Europe ) -- ♬ Dragon of good fortune struggles with the trickster Fox ♬