To me it's clear that crypto is worthless, so I don't see a point in such an action.

In my view their interest, which aligns with that of all other major owners of crypto, is to acquire as much real currency as possible.

Acquiring more crypto by decreasing its valuation is not furthering that.

Maintaining a high valuation and positive sentiment in order to convert buyer's real currency into profit to cash out is what I believe their strategy is.