I can't speak for all HALO investors but I don't think its the CRL per say its the (much further reaching) contents of the CRL and the fear of how far it reaches.
For those unfamiliar with HALO here is a summary of their products and if one believes management the impact:
Hylenex (Approved) - > not impacted HyQvia (Baxter immunoglobulin with rHuPH20) -> on Hold Herceptin SC, MabThera SC, Actemra SC (Roche) -> not impacted. Herceptin filled March '12. Mabthera planned filing later this year. Cinryze (ViroPharma with rHuPH20) -> on Hold
Insulin-PH20 (Proprietary) -> no current trials but my impression the pump program (using Hylenex) would not be but others would be. PEGPH20 (Proprietary) -> not impacted HTI-501 (Proprietary) -> not impacted