So, should I even point this out to him in some way? Is it worth it? Part of me does want to show him the reality of what this will be like, but I just don't know if me saying anything would be worth it or would even matter. I would want to tell him something along the lines you can do what you want in your house, and I will do what I want in mine. Since you fired me, there is no need to collaborate on these types of issues.
Nope .... there are 2 things that pop into my head as I read this.
1st- Understand there is co-parenting, and co-parenting with a MLCr, these are 2 VASTLY different things and you should have a different approach. You are spot on in the parallel parenting approach/concept, there will be a different set of rules in his place Vs yours. Mine is similar, my place is a safe house and less rigid ... my S feels free to express his thoughts and feelings and with her its chore after chore ... her house her rules. I understood long ago I can not do anything to change this, my S has adapted to this and has done well but there is no question whom he prefers to be with ... again .. not my circus nor my battles. Funny thing is he helps without asking and does more at 'our' place than he does with her ... not right or wrong but we do have different parenting styles.
2nd ... the statement "Part of me does want to show him the reality of what this will be like". Hopefully me just pulling it out will allow you to see this for what it is ... its that expectation filled statement .. if I just show him the error of his ways he might snap out of MLC and start behaving better .... MLCrs do not like to be called out on anything, nothing but a conflict will come of this and I can about bet my check he is not going to see it your way ... its all about him at this point and he has a fantasy built up in his head about how its going to be and you will not be able to tell him differently ... sadly they have to live it for a bit before doubt sets in. So yeah ... nothing you say/do will matter in this so why add stress to the issue?