with how deeply physical their bond is, i don't think that hollanov ever bothered to develop a safeword. i do think, though, that they developed-- by accident!-- a physical system to tell each other how they are feeling. and it definitely bleeds into their life outside the bedroom, and it's definitely subconscious at this point, and it definitely makes it into the locker room and onto the ice by the time they're both in ottawa.
which means maybe the centaurs have picked up on the fact that hey, sometimes when shane wants ilya to stop doing something, he taps his arm twice. or if ilya wants shane to move one way, he taps him three times. or if he just wants his attention, its a squeeze. which is all relatively normal, and they probably think its cute that they have an unspoken language for communicating with one another.
and then maybe-- by accident!-- it starts taking root as a thing, and then mindlessly troy or wyatt or bood accidentally double pats shane's arm to get him to stop talking to ilya for a moment, and shane thinks for a moment, that was a weird coincidence, and moves on. but then it happens again, and then maybe luca squeezes his arm to get his attention and then bood taps him three times to get him to move aside so he can walk past and shane feels himself flush to the ears and catches ilya's eyes across the room and ilya definitely noticed that too. so now what? they can't full well ask them to stop without saying, hey, so this was a sex thing. but it'd be weird to let it continue... right?