Vanguard don't really need to juice their stock like blackrock, I can see why they would be more chill on bitcoin, and wait for it, the market is still new, there aren't options yet which could make it more attractive for them to allocate and hedge in the future, plus you don't know really how these custodians will work out

The amount of money that flows into Vanguard is massive and those people aren't exactly looking to be made rich, they're already rich, they just don't want to lose it, guess its brand and protect what you have first approach