However this happened because the map has both a low approach rate and ninja spinners.

Anyway my main point of supporting Auto+1000 spinners is for having 2/1 spinners in some maps that have no other choice ( http://osu.ppy.sh/s/14234 ). Obviously this kind of spinners should call for a little delay before the next hit-object, but i don't feel comfortable enough to set a specific rule for it and I'd say to go with a guideline.

It's easy enough to set some safe limits as rules. For example: "A spinner less than 500ms must have at least 500ms recovery time. A spinner greater than 1200ms must have at least 250ms recovery time. For spinners between these lengths, use common sense but don't allow less than 250ms recovery."

These numbers are off the top of my head and can be adjusted.

That's an idea, but then we face notes ridiculously far from the center of the screen ridiculously soon after spinners. I did see in a map a rather long spinner followed instantly after (1/2 after at 179 BPM) by a note that was in the extreme top left corner.
Some players judge distance from the center of the screen as what to use as spacing after spinners. The situation described above completely counters this and is extremely surprising and unintuitive. Not to mention that said note is extremely hard to catch.
Something should be added as a rule/guideline about this.

What you guys are saying is to add a rule/guideline for something that is easy as hell to spot while modding and that may be justified for insane difficulties depending on the map itself.
I never found myself complaining about spinners as long as i'm able to get at least a 100 on them (and this would covered by the Auto+1000 rule) and players don't even care about a beat being 500/400/300/whatever ms apart from the end of the spinners.
Short spinners are not used as much as it seems and it's fairly easy to understand that a Auto+1000 spinner followed by a 1/4 note placed in a corner right after is stupid or not.
If you want to add some generic guideline about it I'm fine with that, but please keep the milliseconds thing out of it because it has no sense at all.

The easier to understand & justify a rule is, the more reason we have to add it, not less.
It's an unfortunate consequence of the current social climate of the community. Certain mappers will choose not to use their heads, and attempt everything unreasonable in their maps if it doesn't directly violate a stated rule. (And often even if it does!) When a BAT abstains from ranking it, they'll claim that BAT is corrupt and create a scandal.

The millisecond thing is already implemented in AIMod and should be obvious.

Change this rule to be based on a future AIMod addition which will base spinner requirements on the difficulty of the map (taking into account recovery + length), and not use auto to judge required length.

Well Ekaru wanted to say something about it