He doesn't really need more to sign, lake, except perhaps to solidify his position as lead counsel in the consolidated suits and a way to figure out the fee split with the other attorneys filing.
This is not being handled as a mass tort, where direct representation is important, but as a CA, where he and the other attorneys will be entitled to fees on a settlement for the entire class other than those who opt out-if of course they prevail in the suit.
If you think this frivolous, it ain't. Attorneys do not take contingency fee cases unless they think there are some deep pockets