Why the modified tccd file can pass the signature verification?

[moqi2011]

Recently, I am studying this project to see if I can use kfd to make it work on a newer system version. I have a doubt about how "patchTCCD" passes the signature verification after modifying the tccd file. I found that he only modified a few The pointer and added a string, and did not deal with the signature. I've tried modifying other files and it doesn't seem to pass the signature check. Is this a bug or a feature? Will it work on newer system versions? Can other executables be modified? Are there related articles describing him?

Thanks.