He is the prior at the Houston, TX priory.
I would describe him as a silent supporter. In the early days of the Crisis, he told his parishioners (during sermons) that they should go home and get on the Internet and get themselves informed about what's going on.
Doesn't sound like the "party line" to me
Also, when the 8 disgruntled parishioners at my chapel wanted to "have something done" about my wife and I holding volunteer positions despite our position on the SSPX Crisis (and our running CathInfo), they didn't go to our priest, they didn't go to our prior (Fr. Zendejas) but they went all the way up to Fr. Rostand.
Why? Because they thought they wouldn't get anywhere? Probably.
Last but not least, another priest at that priory was Fr. Dardis -- you might recall that he officially went independent a few months ago, joining the Resistance (though not the Pfeiffer branch of the Resistance).