Both require similar moviemaking techniques as well as the huge budgets that go along with them. Both types of movies also tend to be slotted in as "summer time" blockbusters... Im not the guy you are asking the question to, he might have been thinking along different lines, but that is at least one way they could be lumped into the same category.
I kinda think that works in my favor. There are good low budget science fiction movies. Super hero movies, less so. Especially in the post Jurassic Park era, where the bar for effects has gotten quite high.