Reads like it’s not copying the parent, it’s manually constructing the env dictionary to be passed to execve explicitly. I do this in one of my tools at work because developers were exfiltrating secrets and hand jamming them into .env files.
I'm not being pedantic. I just want to read about injection when I'm promised injection :-) because that'd be technically interesting for me. Plainly calling execve isn't so much, I have the manpage here already :-)