Hey!
This looks like a cool project! A few things about the enjen.net/asn-blocklist api! You could use it to pull IP lists of ASNs. That way you would simply need to specify the ASN in a config file. You could then recheck every few days for updated ips!
https://www.enjen.net/asn-blocklist/...on_split&api=1
Just grab everything inside the ipv4s array and away you go! Remember, TF2 and the source engine at the moment don't support IPv6 so it would be worthless to smash those in!