Sure enough, if you look at the pages of the two games the OP in that thread mentions Rayman Legends and Splinter Cell Black List there's no mention of additional DRM, which of course there wouldn't be since it's not mentioned in the fine print on the page to grab it from.
Even though it's due to their own ignorance, it still seems a bit troublesome that some people might think they are protected when they aren't. Really Valve should put their foot down about this nonsense, but yeah, like that's going to happen.
I don't suppose that pulling from the Big List of 3rd Party DRM on Steam is still on the table now that it's been wikified?
I re-wrote the uplay detection script for the next version of Enhanced Steam and it correctly identifies the new Splinter Cell. I don't think they've announced uPlay for Rayman Legends - Rayman Origins didn't have it so I think (at this point in time) it's generally assumed that Rayman Legends won't have it either.
Pulling data from the PCGamingWiki for this DRM list might be something that I move to in the future if developers keep pulling shady stuff like this. They are working on getting an API set up for Enhanced Steam that I'll have access to this and other data going forward (including links to their wiki entries for each game, etc) so I'll keep an eye on it.
Of course we both know the best way to get publishers to disclose this: demand refunds from Valve. Legally speaking, you're entitled to a refund if you are presented with a EULA after purchase that contain terms you do not accept. Fortunately (in the US at least) the Steam Subscriber Agreement (a contract) doesn't trump this consumer protection law. If people simply started demanding refunds from Valve rather than saying "Ok, I guess I have to jump through all these hoops to play Splinter Cell", we probably wouldn't be having this discussion.