See...the thing is, many male abusers are misogynistic - and I believe that's what she's basing much of her assumption off of. Here's the problem (apart from the obvious, of course) it isn't relegated to just looking at women as solely sexual beings. There is a deep level of disdain towards almost every single woman in their lives - mother, sisters, and sometimes even daughters too. Not playful, joking flirtation but a very enmeshed immense disrespect across the board that's very difficult for them to conceal.
And I well believe she knows that - but it obviously doesn't fit with her theory if Travis deeply loved his sisters and practically worshiped MumMum.