The 2006 IAU definition was explicitly scoped in a limited way so that it does not apply to anything beyond the Solar System.
Planets outside the Solar System are not held to the same level of scrutiny. Over 6000 planets have been discovered outside the solar system, and none of them are required to clear their neighborhoods to be designated as planets. The IAU’s Official Working Definition of an Exoplanet can be read at: https://www.iau.org/CommissionF2/CommissionF2/Documents.aspx
So, if someone really thinks we ought to have a universal definition for what a planet is, then they might start by having a word with the IAU.