The "SRAM Powerlinks only work on SRAM chains" is both a marketing ploy to sell more SRAM chains and the legal department covering their arse should one catastrophically fail on someone else's chain.
I've used them for years on all sorts of chains with never an issue. That stated, they are hardest to put on and take off of Shimano chains - the fit is sometimes so tight that it creates a frozen link. Usually, I will try another and work it until it loosens up.
55/Rad