Hi, thanks for raising this topic. Whilst this snap is similar to the Ubuntu Mate Welcome app (allows installation of software etc), it is also quite different, in that it is not associated with a particular Ubuntu / distro flavour which to my understanding was one of the prime reasons why the Ubuntu Mate app was allowed by @niemeyer in Classic confinement request for Ubuntu MATE Welcome and Software Boutique - the process for reviewing classic confinement snaps specifically says that third-party installer applications are not a supported category for classic confinement.
As such I don’t think this fits in the current definitions.