Strong evidence? No. Rather the opposite. There's not much wiggle room.
Interpretation of the summoning? Read 532 again. It specifically says all forms of travel and scrying were blocked ... except summoning. Not "many forms of travel," or "a few key methods, but not including calling." It says:
Teleportation, scrying, plane shifting, dimension doors, locating creatures, sending ethereal jaunts, you name it, it blocked it.
For some reason, Dorukan built a specific exception to summoning spells into the Cloister's effect. I still don't know why.