Both this comment and the article make the claim that the GPL will cause the changes to be contributed back, but this is wrong.
It will cause the changes to be *released*. This is very different than contributed back.
If you scour the internet, you will find hundreds if not thousands of releases of the linux kernel by companies that are not used by anyone else, and contain slight mods here or there.
Same with any other GPL package.
The number of folks that *contribute changes back to the project* instead of *release the source as a dump* is incredibly small.
Anyone who has ever worked on GPL projects knows this is how it works in practice.
The theory that they will find it easier to send upstream is misinformed at best, as is this will just happen because it's "better for the companies". The vast majority of companies of this scale see no advantage to spending the time to upstream it, since in reality it doesn't magically get maintained if you do that, you still have to spend near the same amount of maintenance work in most projects.