I was learning in a shul where I was # 10 for Mincha. I was willing to stay there, but I did not wish to daven with them. However, it occurred to me that by not davening with them, I deprived them of tefilla b’tzibbur, according to Rav Moshe, who requires 10 people saying SE. Do I have the right to stay there and daven later (not with them), if the later minyan is better (due to pace, or b’rov am hadras melech, or makom kavua), even though I am depriving them of tefilla b’tzibbur? [Personally, I try to daven with 10, but in this case it is better for me to daven in a different minyan, even though I don’t mind staying in the first place and learning).]
This is a gray area. Since they will have a minyan, although if you will daven with them it will be better, but you don’t have to deprive yourself of the learning and davening in a better place. However, since it is a gray area, you will have to evaluate each situation for itself.