...If I may...
- Subtropical lows are lows that carry both tropical and extra-tropical characteristics; these include a warm core in the lower levels, and cold core aloft.
- Tropical lows are strictly fueled by latent heat release and convective processes and therefore, are warm core from lower levels through the vertical depth of the system.

This system's origin was originally the southern aspect of a mid-latitude trough that bifurcated and pulled away toward the SW, as the trough was lifting out in the vicinity. At the instant of this sudden "cut-off" scenario, it was a cold core system left to spiral down in the vicinity. But the waters there are still mild to warm, but not quite 26C, but close.. Provided conditions are right, you really do not actually have to have the water temperatures be ideally 26C or higher; proven by the event in the far eastern Atlantic in recent times.

It is possible, that given time, it will acquire subtropical characteristics (if it hasn't already) and be subsequently named, because the surround environment is actually pretty good, featuring variable flow at U/A, and the oceanic heat content in the area is at least sufficient for slow development - provided the surrounding environment remains non-hostile. If the system assumes a S drift/motion, its chances would only get better for encountering warmer waters still... But, I haven't actually analyzed the SST out there so much of this latter thinking is based on climatological understanding alone.