Valve is generally supportive of mods (hell, a Portal 2 mod was just released a few days ago) but it seems like recreating Team Fortress 2 was pushing it... Really sad, honestly. I really hope Valve would just strike a deal with these devs and make it official rather than throw away the insane amount of effort they put into re-building TF2.
IP laws should have a "use it or lose it" clause to be honest. Otherwise companies become lazy and repackage the same shit in a new skin that you have to pay for.