Certainly there are several ways to look at it, but it's more than just semantics.
The magazine disconnect is a feature that some pistols have and some don't. IDPA allows pistols that have magazine disconnects and it allows pistols that don't.
The SR9 has a magazine disconnect that was (I believe) purposely made to be very easily removable by the user to allow the pistol to be configured as desired. That way, Ruger can sell the pistol to all 50 states without worrying about specially configuring pistols for shipments to those states with (idiotic) requirements in configuration, such as those that restrict magazine capacity to 10 rounds.
There are those that might describe such a 10 round magazine as a "safety" magazine. If I took a California pistol and, standing in Oregon, inserted a 17 round factory magazine, would I have disabled a "safety", and thereby rendered it illegal under IDPA? No, in my opinion.
I believe it could be taken to quite an extreme, because everything on a pistol is there, essentially, to enable the pistol to be safely operated. Change the sights? Sorry, you changed the factory 'safety sights', that's illegal. Custom grips? Sorry, you disabled a 'safety', because the factory grips enable you to safely grip the pistol, and we have no way of knowing if the aftermarket grips are safe.
JMO, but the magazine disconnect is just a feature of the pistol, not a safety, that when installed or uninstalled allows it to function one way or another.
YMMV