Ralph Goodale, the guy who posted this SQUIRREL!!!! look over here and stop talking about Lav-Scam video, also voted against Gay Marriage. HOMOPHOBE!!!!
A lot of people believed that Marriage is a certain thing. Gay Civil Unions are fine, but they aren't marriage. People evolve, there was no real threat to Gay or Abortion rights in Canada. Bringing it up is just fear-mongering, which is all JT seems to have to run on right now.
There are people in the CPC that probably do think Gay Marriage rights should be rolled back, but they won't ever get elected or re-elected with policy positions like that.
Whether Scheer believes in it, or not, is less important than what he'll do as PM. It would nice if he came out in full support of Gay Marriage, but he's probably worried about losing support on the other end of his party to the PPC. It's politics.
You see the Republicans gearing up for a similar tactic in the 2020 election where Democrats will have to be counted on their views on the BDS movement because certain members of the party are for it.