This is just capitalism in action. This is a variation of the "free rider" problem.
The logical extension of restricting entire countries because you can't derive revenue from them is to block *any* group of users that you can't derive revenue from if you can figure out how to do that.
The corollary is that you want to attract customers who you *are* likely to derive revenue from, so you create content to appeal to those groups.
If the marketing geniuses figure out that senior citizens are "unprofitable" as internet consumers, maybe that means blocking that group. Of course, that will probably anger people who realize that someday, they will be old and will therefore be blocked, so the strategy could backfire. It's a lot easier to block people from, say, Africa, because that affects someone else, a group that most consumers can't picture ever joining. It's also a group that can be blocked as a group without sacrificing valuable users.