Shouldn't be a problem if that's what they're doing with their spare time. For all that we know Nylena's roommate has a job, is satisfied with it for now, and doesn't feel like working in-between working. People can find the oddest things to while their time away. For instance, personally, I have no idea what the appeal of stamp/coin/bug collecting is.
In the end, if the activity doesn't get in the way of priorities, it should be neither useful nor useless.
But why listen to someone who has nothing but free time, right? I'm twenty-five and I've never held an official job in my life. ;/ Still, in said spare time, I do a lot of browsing to pick up information and learn things. Most people will likely call that a good activity; but, is it really, when the vast majority of what I learn can't be used and is forgotten?
Maybe I'm making this out to be more than it is. But I can't help seeing things from multiple dimensions. I'm in no way trying to justify my own lifestyle.