Tim Williams wrote-
Yep -- but it will still be a troodontid (and probably a quite derived one). That should be unambiguous enough for not harming its function as a specifier.
Here's the problem... If a taxon is deemed to be a nomen dubium it becomes an invalid OTU, and so must be excluded from phylogenetic analyses. Therefore, its exact position in a phylogeny cannot be determined. I would think this would mean that the taxon in question would be invalidated as a specifier.