Unless other pilot groups at other airlines received the same representations from Boeing and relied thereon to amend their CBAs or other contracts, then any action by those groups would have to proceed under a different legal theory.
Reading between the lines the misrepresentation they may rely on is the data supplied, and data not supplied (and subsequently found to be withheld) to the FAA to receive the amended TCDS.
I guess it is similar to a drug company not providing full disclosure when getting a drug approval from the FDA.
The representations you identify were made to the FAA, not to some unknown, future, potential passengers and were not made to induce those passengers to do anything. Although that does not definitively defeat the claim, because the representations were not made to some unknown group of passengers, it would be very difficult to identify actual reliance by these unknown individuals. Specifically, when Boeing made the representations to the FAA, what action did the unknown, future, potential passengers take in reliance of the representations? They did nothing. They didn't purchase anything from Boeing or from anyone else because of those representations. Reasonable reliance is an essential element to the tort of misrepresentation.
Your drug example is not applicable. First, people who didn't purchase or use the drug have no claim regarding representations made to the FDA. Second, people who do, in fact, purchase the drug, would have to demonstrate that but for the incomplete disclosures, they would not have used the drug. This is a very high hurdle since few, if any, of the potential plaintiffs would have been aware of the information provided to the FDA and, thus, would not have made any decision based thereupon. Finally, any potential plaintiff would have to demonstrate that the lack of disclosure actually harmed them. If the drug is still safe, no lack of disclosure could have caused any harm and thus no claim is viable. Lack of disclosure, in and of itself, is not sufficient to state a claim.
Accordingly, in this scenario, most plaintiffs would sue principally for product liability and use the lack of candor as evidence that the product was defective. However, they would still have to show that the product caused actual harm to them; simple economic loss is not a sufficient harm.
Since no passenger purchased a MAX from Boeing and since no passenger was actually harmed, there is no products liability claim either unlike your hypothetical drug case.