On the contrary. If you understand enterprise FOSS, then you understand that one of the primary benefits of FOSS for the enterprise contributing customer is the ability to to make the software more relevant for the enterprise through the enterprise's contributions to the FOSS project, at a rate which is typically unfeasible, if even possible, for closed commercial products.
By splitting up the open-source Docker CE codebase into smaller projects, each smaller project is more approachable to outside potential contributors. If Docker can succeed in increasing the number of contributors to the Moby projects, compared to the Docker CE project, then they'll have succeeded in increasing the relevance of their product in their target market, which translates to more customers, sales, and profits in the long-term.
Of course they run the business risk of a fork taking off, but in the real world, forks are arms races. They're easily won against dead or severely mismanaged projects, but against a project with a well-funded corporate sponsor? Few, if any, will have the resources to put into making a better fork than the original.
And like they said, for the vast majority of their customers, nothing is changing. Their customers bought a Docker product yesterday, and they're buying a Docker product tomorrow. That branding isn't changing.