I personally don't think that's the reason she was dropped from contract. But you can't really stop others from having theories.
The rest of my post addresses reality. How viable a major character is seen on the romance/sex front absolutely, 100% affects how they're written.
ALL front burner characters on GH are considered romantically viable. If they aren't? They aren't front burner.
Kevlaur was a pleasant romance. But like Tony and Genie have both said, "happily ever after" is the death knell for story. "Nice" romances don't get much screen time.
It would absolutely have benefited Laura if the writers, and producers, saw her as an option for the leading men on the show.
Not sure how anyone can say otherwise.