I think what's confusing is that there are two dynamics here: gender and T/client.

Ts usually try to adopt a "submissive" posture regardless of gender. While a man sitting open legged may be considered an open and honest position in relation to another man, I suspect few women would interpret it this way in relation to a woman.

To impose an interpretation that is counter to the experience of the person who's receiving it, is a dominant gesture in itself, regardless of circumstance or intention.