He didn't act, look or sound like Finnegan in any way whatsoever.
Finnegan was a lanky, loud-mouthed, abnoxious, douche. "Cupcake" was just a thugish redshirt.
Now, I might buy that the hitchiker Kirk passes on the Iowa road was spposed to be Finnegan. (His lankyness and overall look was Finnegan-esqe.)