Yeah, anyone who is threatening to sue over the warrants clearly hasn't actually talked to a lawyer yet. There is no case against them.
An unscrupulous lawyer, though, would take the case and drag it out Sweeney-style, knowing that it has no chance but racking up billable hours in the meantime.
Even the Washington Federal plaintiffs were smart enough to not try to get the warrants overturned. They only want the warrants' existence (and potential exercise) factored into a damage award for pre-conservatorship shareholders. Washington Federal does not ask for the warrants to be cancelled or otherwise done away with in any form. They only want money.