The example given is a good demonstration of sep assurance vs. "they'll never hit in a fit".
Also, sometimes if you look hard enogh, you do have a standard.
Does this one appear in your tool bag;
Transiting to airspace with a different standard.
When two aircraft are transiting to an airspace where a larger standard will apply, and their tracks diverge by 30 degrees or more, and the smaller standard will continue to exist until the larger standard is achieved, the aircraft are deemed separated.
So if you are going from a terminal standard of 3nm to an enroute standard of 5 nm, I would claim that one (if you have it where you are).
Technical loss of sep: I have used this phrase to inform pilots that we don't have the required standard, but they are not going to crash. (received a handoff in procedural airspace coming into radar where there was 18nm longitudinal, same level- loss of sep, but they weren't going to die). Don't think it's an official term, but useful.