Everybody seems to be lurking in comments. I'll just run through what happened.
I'm not sure if you can see that but your edit is put up for review and people vote on it. If two normal users (or one mod) think your edit is poor, they specify a reason and it's rejected. Both reviewers thought this was an attempt to comment so rejected it.
Should it have been rejected? No, probably not.
Even without the comments, I personally would have accepted it because I can see it:
- Improves the answer (makes it more portable)
- Explains why it improves the answer (as good answers should)
- Doesn't change the core answer
- Doesn't make it too specific or less portable (it still works on i386)
If there were a single defining example of a "good edit", this could be it.
But this is the game you play with community review. By design we aren't all the same person and we can all interpret things differently. Perhaps these reviewers just came off the back of a load of invalid edits (it happens) and accidentally robo-reviewed through yours.
One aspect that could be improved on your part is the edit message. That's an opportunity for you to explain the gravity of the edit and why it's important. You simply repeated the edit in here. Something that might have convinced a reviewer might be:
Improving answer to make it work on multiarch systems
There's nothing to be done about the edit. You could submit it again (if it hasn't already been sucked in by somebody else) and hope for a better outcome but we can't overturn a review outcome at the time of writing.
I'll have a word with both reviewers and point them in the direction of this thread. They may have a different point of view that they want to share. They might learn from a mistake.