So the issue is we have a pretty clear Process for reviewing classic confinement snaps which outlines the supported categories for classic confinement - and in this case this snap does not really fit in the suggested debug tools category - and instead fits more in the unsupported category of 3rd party installers - and so the clear answer really is that unfortunately your snap is not supported by an existing category and so we cannot grant it classic confinement.
As @ogra alluded to above, this is complicated by this being a request coming from a quite senior team member at Canonical, which then leaves folks on the reviewers team feeling some pressure to approve the request in spite of it not fitting within the categories. We want to have clear processes and expectations that we can apply to both internal and external requests and so we really want to avoid having to grant exceptions to snaps from Canonical team members which we would not otherwise grant to anyone else.
As such, if you really need this to be a classic snap, the only way forward is to have a Snapd architect change the list of supported/unsupported categories to make it clear that we can start granting classic confinement to snaps with this kind of use-case.
But for now, this request doesn’t fit in a supported category so we cannot grant it.