Ah, the age old "does sealing use chakra or the Out?" debacle
But yeah, Sealing as an art is blackboxed from we-the-playerbase, and we've been told by the QMs that if Hazou wants to cause a mental affect using Runes or Seals, then that would require Hazou to learn genjutsu, beforehand. Similar to how he needed a grounding in Mednin before he could start on replicating the Chakra Pool's effects.
"Blocking memory transfer" sounds like a mental affect, since it involves the mind: namely, memory.
Maybe there's an argument to be made about Medknow or Mednin, since memory involves the brain? But at that point, though, I'd take it up with the QMs and request an additional ruling.