User blog comment:B214/Question and Answers 3/@comment-25222726-20140717181240/@comment-1359322-20140717233445

Removing weakness =/= to awakening powers/abilities. If it was, the Evil Dragons would be unbeatable by now since they can just add new powers and abilities as they further increase in number. But you don't see any of that. It's the same even with the Vampires, they were just removed of their weakness, they didn't get any new powers whatsoever.

Even the Boosted Gear Replica was made using the remains Issei's previous body, but it is clearly weaker than the original.

So even if Sairaorg were to be experimented on using the Holy Grail, there's still no way for him to awaken the POD since he never had any in him in the first place, at best it may only remove his weakness as a Devil and perhaps strengthen his Touki.