An SSPX priest told me that the reason for the split at the school was because a yuppie family wanted their daughters to play volleyball and the SSPX objected to the immodest attire, they just left and started their own school. So if this story is true, and so many others have opted to follow them to a new school with laxer modesty standards, gender roles, and increased worldliness compared to the sspx school, it does not speak well of it.
I am hoping Town Crier and Smedley see this post so they can tell me if this is true, or if I have been fed a line of bull.