I suspect the question actually is, "Can the USHPA prevent the US Hawks from participating in the USHPA's RRG?"
I don't think they can. This provides the US Hawks with a ready-made RRG.
The other question is, do US Hawks members want to participate?
Some may not, for ten reasons:
1) Many states provide landowners with liability protection.
2) It is not a law that hang glider pilots have third-party liability insurance.
3) If you never fly near people, it doesn't even make sense.
4) It's really expensive. Any claims paid out by the USHPA will require an increase in dues/charges to members to maintain the reserve baseline.
5) One big lawsuit can wipe out the entire fund.
6) That lawsuit will probably stem from joyriding.
7) That lawsuit will probably stem from an accident that has already happened.
8) If joyriding doesn't wipe out the fund, the chances any other claims will stem from paragliding are about 85-percent.
9) Any claims brought by the US Hawks may not be honored by the USHPA, regardless of merit or legal requirements.

10) Who trusts the USHPA after what they've done to hang gliding and to BobK? I don't. I no longer see them as an advocate for hang gliding.