IBM PC was not reverse engineered. IBM published very detailed technical reference manual that contained entire schematic of the circuitry as well as full assembly listing of the BIOS. The details of the IBM PC platforms (classic, Jr, XT, AT & PS/2) were never secret.

Please don't mix up reverse engineering with various clean-room design methodologies.

I will however believe that there were people who were paid to pretend to do reverse-engineering and probably some of them were even paid to swear to that under the penalty of perjury or create an "alternative construction" that served as a proof of reverse engineering.