It's not technically a content model change, because EnableFlow moves the old page and then creates a new Flow page with the same name.

In T105655#2668901, @Catrope wrote:

It's not technically a content model change, because EnableFlow moves the old page and then creates a new Flow page with the same name.

Special:ChangeContentModel can also be used to create pages. This would be useful if the default content model is different from the desired one (the same as the use case here).

This is not as urgent after fixing T146425: If Flow is replacing an existing page, Special:EnableFlow does not attribute the creation, but seems like a valid request.