IANAL, but I don't think your analysis is quite correct.
I think the key is
> It is well-settled that the proper ground for cancellation is the underlying question of whether the mark was in use in commerce, not the adequacy of the specimens
If I understand correctly (and I very well might not), that means that it doesn't matter whether some of the provided specimens were fraudulent or not, in order to revoke the trademark the burden of proof is to show the entire trademark claim was fraudulent, and if there was no fraud, then the trademark wouldn't have been granted.
Deno might be able to make a stronger argument of fraud, if they could show without that specimen USPTO would have rejected the application, or that the other specimen was also invalid, but that would delay the proceedings and require more work for them.
I think the key is
> It is well-settled that the proper ground for cancellation is the underlying question of whether the mark was in use in commerce, not the adequacy of the specimens
If I understand correctly (and I very well might not), that means that it doesn't matter whether some of the provided specimens were fraudulent or not, in order to revoke the trademark the burden of proof is to show the entire trademark claim was fraudulent, and if there was no fraud, then the trademark wouldn't have been granted.
Deno might be able to make a stronger argument of fraud, if they could show without that specimen USPTO would have rejected the application, or that the other specimen was also invalid, but that would delay the proceedings and require more work for them.