How are these people different from Baal worshippers?
I believe Baal worshippers "aborted" their firstborn children after birth, and allowed polygamy, but there is no proof that they allowed same sex marriage. Marriage in ancient Canaan (and later in the Phonecian colonies) was to beget children.
However, it hasn't stopped the PC from making up facts. link
Note he quotes the bible and the later Jewish writings (written centuries or even a millenium later) but doesn't have any proof that there actually was a lot of same sex marriage around, (i.e. where a society actually recognizes and honors the relationship) as opposed to homosexual practices per se. (as in the classical times of Greece, when homosexual relationships were frowned upon but known to occur, and even promoted by some of the intelligencia as "normal")
Indeed, a lot of the Biblical criticism of the Canaanites is thought by archeologists to be untrue or exaggerated (e.g. child sacrifice to Baal):
they similarly dismiss child sacrifice in Carthage (something that the Romans often pointed out as a reason to destroy the city).