Tbf it was hinted in early Wano that he took something very valuable from her
I don’t think it’s that far fetched since it happened in totoland and it was guarded by a sweet commander.
Nah, it’s really brain-dead to me.
Big Mom has canonically been furious for twenty years that Roger managed to steal a copy of her RP, and is fully aware of how valuable the knowledge it has is.
So she has locked it in the heart of her fortress, under lock and key, watched 24/7. Which is all very sensible.
There is no reason to let any member of her empire to carry with them a copy of it in a ship, rendering all that protection meaningless. No matter how strong that member is. Even Katakuri, her number two. Because she knows the value of that info, she knows that the world wants it. The only one that could be strong enough to guarantee protection of a rubbing would be Big Mom herself.
If she wants someone to read it, force them to come to her. If they are too strong to be forced, then they aren’t going to help her anyway.
If Snack wants to read it himself, he can do it from the vault
Oda now needs to invent a full on backstory for an almost totally irrelevant character of him being like a black market RP salesman, BM somehow not knowing that her Poneglyph copy is on the black market and none of the other Yonko knowing either.
And Snack has been allowed to live despite his catastrophic error when BM is wanting to cut Lola into pieces for rejecting Loki.
Very bad writing imo.