No, Valve doesn't care about third party gaming mods. I use mods for 1/20th of my 560+ game library and have been for over a decade.

Also, IronGate developers will never respond in the Steam forums. If you want a direct response, you can try their Discord. However, they require you to verify your account for spam, by doing a one time mobile phone SMS check.

Edited for punctuation. The "No" is about Valve not caring. ^_^