Maybe pshat is that the categorization of yoshvei beis medrash v yosheiv keranos has to do with what you do in your spare time. Do you work 9-8 and then sit in keranos, or do you work 9-8 and also learn on the side?
And that that also transforms the rest of what you do into divrei torah v devarim beteilim. Meaning, that if your life doesn’t centralize torah, even the other important things you do become devarim beteilim, since they aren’t in the service of torah.
I like this very much.
Also, there are other dichotomies in this tefila. Someone who is from those who learn Torah, gets up to learn Torah, works and gets [spiritual] schar, is going towards Olam Haba.
Suppose someone is from those who learn Torah, but doesn’t fit one of the other categories?
So let’s go a step further. Maybe it’s saying that it’s about the attitude the whole time.
You can learn in Beis Medrash, but spend your time following politics and answering silly threads on the CR. That’s a yoshvei Kranos. Or you could work, but learn in your spare time and respond to Torah-dik and halachic threads. Then you’re a Yoshvei Beis Hamedrash.