My take here is slightly different. I don't consider that question to be cross-posted at all. While it is true that posting the same question on multiple sites of the network is frowned upon, posting different versions of the same question to target the different audiences on each target site is not. This has been mentioned in various places by various Stack Exchange employees:
Robert Cartaino (Director of Community Development for the Stack Exchange Network)
If you do not receive an adequate answer, then it might be okay to ask your question again to another group of users — as long as the question is on topic and appropriate for that second site.
But cutting-and-pasting between two sites is never okay. If you want a different perspective, you should phrase the question specifically for that group.
Jeff Attwood (co-founder of SE)
This can be OK, so long as the question is tailored to each audience on the different sites and is materially different in each case. Just to be 100% clear, copy-pasting a question across sites with no changes is considered abusive behavor.
Shog9 (Community Manager for Stack Exchange)
Cross-posting is discouraged when it's someone spamming multiple sites without bothering to identify the appropriate audience or tailor the question for each site, but if you have a question that hasn't been well-answered on one site - whether that's another SE site or something external - re-asking it in a more appropriate venue is perfectly fine.
It is also ok to ask two different versions of a question but you MUST tailor it to the audience on that site. Copying and pasting would put you on the road to account suspension.
My interpretation of all the above and various other meta threads I've read over the years is that bad cross-posting is posting the exact same question on multiple sites. Posting different versions of the same question on multiple sites is fine.
In this case, the OP took the time to modify their question to fit the different audiences. They didn't do a direct copy/paste. Granted, the original version of the question was more similar (OK, almost identical) but the current incarnations of the two questions are quite different.
In addition, the OP has tried three different distributions. Mint, Elementary and Xubuntu. The first two are explicitly off topic on Ask Ubuntu but on topic here. He therefore quite correctly posted the two versions on different sites. This seems to me to be precisely what we want our users to do.