I know in Ontario there was a scolarship for those who identify as LGBT (there really is a scholarship for everything these days), so maybe it's similar, or they wants statistics to improve facilities and services. (The university in my city has a Trans support group that requires a letter from one of the school's councellors, who works with LGBT students in order to join, weeding out anyone who wants to go just to cause trouble.)
I highly doubt they would use it to eliminate applicants. It seems unnecessary to put those questions on the application unless it relates to residence housing. But I wouldn't be so quick to assume they just don't want gays, lesbians, bisexuals and trans people. These days that kind of discrimination could get them in a lot of sh*t.