Basically, the idea is "You can't tread on their Trademarks without irritating them, but you can get the same effect as long as you can clearly establish it's Legally Distinct, and even if they bitch about it, they won't be able to cause any official interference with your acquisition and deployment of such resources."
Notably, the Mechanicus is generally going to be inclined to give us a bit more wiggle room on the definition, because we're a reliable source of a rare and valuable specialization.