I think the obvious thing to do is go with the larger current user base, so go back to the ROS 1 style. That is if consistency is the only thing that matters, but I see it as improving what was in ROS 1 to make that message more consistent with the others. By and large the rules we’re enforcing in ROS 2 were the common convention in ROS 1, it’s just that this particular message was different from the other ROS 1 messages, so when we enabled the enforcement it was out of line already.
For me the obvious case solution is to provide a linter, enable it by default, and provide a convenient way to silence the linter in particular cases that you’re unwilling to change, a la # noqa.