What’s wrong with this edit It added a link to the iOS version, without making the answer any longer or taking any more space on screen.
I can‘t speak for the person who rejected the edit, but reading the rejection reason might give a clue:
This edit does not make the post even a little bit easier to read, easier to find, more accurate or more accessible.
There already is a link to the product site (from where both the iOS and the macOS store can be accessed). Adding a dedicated link to the store doesn‘t add value (it even may break if the vendor releases a new version as a new app).
Also keep in mind that an edit in the review queue must be reviewed by several other users. Let‘s make the most of their time by making the edits substantial.