Filing for a patent can itself be a functional scam.
My brother invented a new kind of hi-fi speaker system. We took it to CES and wowed people. More than one said he almost passed us by, because he thought we were a ripoff of another (inferior) product.
That established company had ripped us off.
The proof? Some of their advertising copy used verbatim terminology and phraseology that my brother submitted to the patent office.
They had money and name, we had neither. We did not sue.
My bet is that there are plenty of crooked patent clerks looking for a little side action.
Did he receive the patent? If it was clear infringement, there are plenty of lawyers who would have taken your suit on a contingency basis.