There are a lot of monotypic taxa on iNat, and there are also a lot of observations that get stuck on a monotypic taxa and never get identifyied because the taxon experts go to the subordinate taxon, not the monotypic parent taxon. In my opinion it does not make any sense having identifications be on the monotypic taxon because obviously the identification could be much more specific with the same provided information.
This feature could be done in many ways, but I would consider the best one to be the iNat page directly identifiying monotypic taxa as the subordinate taxa. This would probably require an option in the taxon page to mark it intentionally as monotypic, or something like that, since a monotypic taxon might be “monotypic” on iNat because only one of its subordinated taxa has been added at that time.
Other options could be made, like pop-ups, but I think that would be less efective.