what a nightmare to read. i wish i could say i have never worked with any company so apocalyptically dysfunctional as to need a policy like this.
after 5PM on a weekday and for 100% of the weekend, the default expectation should be that 100% of teammates are not working and are unreachable, even if there is an "emergency". yes, even if it means you or the team is blocked from doing something because you need their input. yes, even if it is "just one tiny question". yes, that means that clients will get mad sometimes.
the team doesn't need to be pulling together to ensure that one person's time off on a weeknight is not interrupted. the team needs to be pulling together to tell management that work stops at 5, every night. then, they need to follow their own rule and be unreachable by 5:01 PM, as a group. this is a problem of labor against management, and the solution is for labor to organize aggressively and set ground rules rather than being picked to pieces by their own sense of industriousness and their desire to please authority by working longer than required.