I don’t think I’ve ever heard it claimed that MIRI said this outright. The usual argument AIUI is: MIRI staff endorse/believe-in TDT (not that MIRI has stated it as organizational policy or anything), TDT endorses not paying off blackmail (and this is obvious/well-known), therefore MIRI staff violated their endorsed (and also, importantly, correct) principles.
I don’t think I’ve ever heard it claimed that MIRI said this outright. The usual argument AIUI is: MIRI staff endorse/believe-in TDT (not that MIRI has stated it as organizational policy or anything), TDT endorses not paying off blackmail (and this is obvious/well-known), therefore MIRI staff violated their endorsed (and also, importantly, correct) principles.