Verification that TLS keys are mostly generated by OpenSSL and PGP keys by PGP/GPG are sanity check that method actually works.
If it will turn out, that particular library has vulnerability, one can quickly search for other vulnerable keys from large datasets like IPv4-wide TLS scans.
If it will turn out, that particular library has vulnerability, one can quickly search for other vulnerable keys from large datasets like IPv4-wide TLS scans.