The fact that it is a open linux device and I can launch in to KDE is the reason I got it. If it was some proprietary OS like other games consoles or Windows, I wouldn’t have bought it. The Steam Deck is such a breath of fresh air compared to how hostile other consumer electronics have become.
The anti-tampering solution sounds like some trusted computing bullshit like on mobile where banking apps will refuse to run if your device has a custom rom or non-locked boot loader. This would be how anti-cheat software could continue to lock out linux.