Pros who use their shooting shoulder

Well, you know, I think this whole "locking" things strategy is at best misguided. I mean if you have a huge, obvious problem with some part of your physique, then ok, but as a general recommendation? Nah, I don't think it's a good idea at all. Humans are not built for such robotic movement, and it's really hard to generate big power doing stuff like that.

It all came about because of the slick cloth, anyway. The old-schoolers were for the most part not doing it, and those who were, suffered a little from the lack of power. Nowadays it's all about accuracy, so the power is no longer needed, which IMO is bad. Even so, "locking" joints is IMO bad and can lead to injuries and strains, even with gentle movement. A friend of mine jumped off a very small ledge, locked his knee and messed it up completely. 3 surgeries later and he's worse off than ever. Keep the shoulder still if you want but I'd be careful about locking it. Even without impact, pulling your shoulder back in a forced manner all day long cannot be good for your tendons, long term.

I'd add Mika to your list of non-lockers.

Mike Davis is probably the most obvious

Most of today's pool and snooker coaches advocate on keeping the cue as parallel to the table as possible. The idea is that if you accidentally applied sidespin, keeping the cue as parallel as possible will minimize the error, so to speak. But if you watch some of the top modern day players, you'll notice that they actually jack up their cue in the address position, and their cue levels out at the end of delivery. Just watch Shaun Murphy, Efren Reyes, Ronnie O'Sullivan or Mark Selby.

https://youtu.be/yyfsEYHGt8k?t=270 - In this clip starting at 4:30, Steve Davis talks exactly about this trend.

They also advocate not to bring shoulder down on your follow through, nevertheless many pros bring down their shoulder during follow through contrary to the pendulum stroke.

In my experience, the key seems to pick a form that feels comfortable and be consistent.

Mike Davis may look like a See Saw when you watch him, but he made it onto a Mosconi Cup Team and is a heck of a player. I got to talk to him once about his stroke. He said he knew it looked weird and against what many coaches would teach, but he also said it enabled him to feel comfortable and it was the stroke he was most accurate with.

I've noticed, and I want to be clear that I am NOT saying throw fundamentals out by any means, but now that I'm getting back into playing, I am shooting better than at any point in my life after a two year break. I'm not mentally thinking about my stroke, I'm just lining up the shot like I know for position and shooting it.

I think the danger for a player is to get so worried about doing the "right" stroke that it never becomes an unconscious muscle memory movement. As long as you are in alignment when the cue strikes the cue ball, it will still go where you intend. Freezing or locking can potentially decrease unwanted movement, but if you focus more on holding still than making the shot, I can tell you you will miss a heck of a lot more shots. Pick a stroke and get consistent in it, and I think you'll see improvements.