Q. If a person who finished davening is learning Torah, and there are people who need him to help with a minyan, is he obligated to go and help them, even though he will lose time from his learning (because he doesn’t learn during chazaras hashatz and he cannot learn out loud during the quiet SE)? Even though they could get someone from the street instead of disturbing someone who is learning? If the person refuses to go to them because “Talmud Torah keneged kulam,” who is in the right?

A. Horav Shlomo Miller’s Shlit’a opinion is that there are several variable unknown factors at play such as avoiding creating a machlokes; how available are other people to join the minyan; how disturbing is this to one’s learning; can one stay a bit longer for learning and compensate for the loss, etc. Therefore, The Rov advises that the shaile should be asked to a local competent Rabbi, who is familiar with the details.
The Rov also mentioned that you can continue learning during chazoras hashatz when needed.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a