I studied the loops too. this is a complex system and I see why the NHC is alluding to sub tropical...the surface feature is where we have suggested, BUT ther is stlii an active and well developed upper low behind and to the SE (now) of the surface low. I think the upper low has shown remarkable resiliance and it still is very much influencing this system.
Until this surface low sheds the upper low It may never be purely tropical. As it seems now this system must still be dependent on cool dry air drawn in by the upper low for some of its energy.
Any way that's how it looks to me.