I tested it out just now, and I got 20 points selecting this answer. So it seems we'd get the 20 points for the best answer, but we wouldn't get the 2 points because it's someone else's question.
Not getting the 2 points is fair enough, since we shouldn't really benefit from selecting answers on other people's posts. The 20 points can be debated, though I think if a mod selects their own answer there's going to be a reason that isn't related to points.