To my understanding it is consistent but a little confusing as in any items list. e.g. articles. A button shows the state but change to the opposite.
Click on green (action) button in the item line and it becomes disabled (blocked, unpublished).
Click on green button in the toolbar and it becomes enabled (enabled, published)
On single item page
"Block this User" Yes/No marking the red No
is the same as
"User is enabled" Yes/No marking the green Yes

I would prefer the second but not a change in 3.x

Edited.

 <hr /><sub>This comment was created with the <a href="https://github.com/joomla/jissues">J!Tracker Application</a> at <a href="https://issues.joomla.org/tracker/joomla-cms/10812">issues.joomla.org/joomla-cms/10812</a>.</sub>

Yes, I know that it is the same, like all Joomla users that went through the learning curve.

But all novice users have to first guess that it is the same, because of terminology inconsistency (due to historic reasons: It was "Blocked" too in User manager long time ago, then someone changed it for consistency with other article and so forth views as well as logic to have green marks when things are ok to "Enabled". But forgot to change it in user edit view. All of that was long time ago.

I see no problem in fixing that in a 3.6.0 or 3.7.0 release. Maybe not in a "patch" release. No need to wait 4.0.0.

Pull requests are welcome

One small issue is that "Block a user / User is blocked" is probably understood. Not that obvious is, that the opposite to enabled is blocked or that disabled is the same as blocked.

I'm not against a change though.

Closed as we have the start of a PR for testing #11421