The general rules on what are 'good' migrations are that the question should be
on-topic on the target site
not on-topic for the 'source' site
The last point is important in the sense that the original poster has made some form of choice of where to ask: it might be accidental, but it might equally be deliberate if the question is arguably on-...
I think it would be great to have these migration paths. Another helpful migration target would be Super User, for questions that don’t involve *TeX after all. We get these questions occasionally; some of them were simply asked on the wrong site, others are just more likely to get a helpful solution when widening the scope of possible tools beyond *TeX.
In such cases such posts should be flagged on the current site to be migrated to TeX.SX. We TeX.SX moderators can't do anything from here exact flag it ourselves. However, this particular post seems to be too old for migration, as the flagging dialog tells me.
These old posts should not be migrated from SO, because:
The new policy is against migrating old questions that have already been answered, partly due to problems with the handling of reputation, and also because these migrates are not held to be constructive. See How to migrate old questions to a new graduated site. Instead, questions that are off topic ...