Yes, at this time, that is correct. Whomever initially defined the app, is the only user who can modify the app’s definition at a later date.
To be clear, modifying an app’s definition (how the app is defined for developer’s needs on Marketplace), is a wholly separate use case than modifying an app’s configuration (performed by Owners/Admins/Users who install apps).
We understand this is not an optimal experience, but it does not prohibit enterprise developers from successfully building amazing apps with Zoom Marketplace (we have some of the largest enterprise organizations in the world happily building stellar apps using Zoom Marketplace). 