I could definitely hear that learning during an Assur time is both a Bizayon to the learning and the Davening, though, which would make it worse than checking email, which is just a Bizayon to Davening.
A. I tried to preempt this taanah. My personal feeling was (and is) that the reason something would be a bizayon to davening is because you’re showing that what you’re doing has more importance than the davening. It follows that a man checking his emails shows a much lower level of respect for davening than the person learning during davening, since torah is yikarah mipninim and all of kapitul 119 etc.
B. There are times when shmoozing would be assur and learning isn’t.
Torah is about much more (and much less) than gaining knowledge or even gaining an understanding of HKBH. It is because Hashem wants us to, which is both the simplest and most complex reason imaginable
It’s an age old machlokes of what torah lishmah is. Noone says though that there is not more to torah than just that.