I don't see that they're saying that. I think they're saying it's very important for UBC to get some marginalized people into these positions, so they're making space for such a person. It doesn't mean white men are bad. (And technically, FWIW, the passage doesn't explicitly count sexual orientation as a dimension of marginalization.)

By definition it does mean that - they have identified a problem (something bad; too many white men) and a solution (a way to make things better; get rid of them).

Clearly it's painful to accept this, but banning people from positions on the basis of their race or gender is racism, hateful and always has been. Whatever their motivations are or are claimed to be is irrelevant. The claim that it isn't racism if it's against "powerful" people i.e. whites is a lie.