Mods are non-commercial products. Because of this they can get away with things that a commercial release could not. Specifically, it appears mods can circumvent copyright laws, as the amount of copyright infringement that modders get away with is simply shocking.
This sentence is wrong.
Mods can not
circumvent copyright law, it still applies to modders completely, and it has been applied several times over the years. The only thing a mod using copyrighted assets can hope for is for them to fly under the radar; as soon as the IP holders (or rather, their lawyers) wake up and bother to file a DMCA notice (or whatever your local equivalent is), that mod is gone.
Speaking of Aliens, mods can seemingly get away with using entire licenced IPs (Intellectual Properties), such as the Aliens mod for DooM.
Again, wrong. If an IP holder decides not to enforce their copyright or their trademarks, that's their decision; but the threat of enforcement will always exist (See: The Stage 9 thing
, or literally any Star Wars thing).
You're making a general mistake in the article in claiming that "non-commercial" means or carries with it "non-infringing". That's very, very wrong; "But we didn't make any money off it" is not a legally valid defence against "you violated our copyright".
I get the intention of the article. Making games your own by modding them is awesome. But saying "....and you can totally get away with copyright infringement!" is just not true.