Proceedings-level paper but no proceedings invitation
First off, "a note [explaining] our point of view" sounds like a perfect use of arXiv, or of a technical report service if your institution offers one.  

There's no delay and no formal procedure necessary, and if it turns out to indeed be useful to the community, then it's readily citable.  Furthermore, there's certainly no shame in putting "side" results out in these more informal format, particularly in a community such as mathematics that is generally used to sharing pre-publication materials.

In parallel, if you think it rises to the level where peer review is appropriate, I see no reason to avoid submitting it to an appropriate community journal---no need to wait for an invitation to a particular venue.  

In short: if it's worth reading, it's worth making available, and the scientific community can surely decide if it's finding it useful or not.