Exploiting a Minotaur's horns

[coredump]

Nope.
Unearthed Arcana is a collection of ideas, hastily penned, with almost no regard for proper wording from a mechanical perspective, which is hardly, if ever, edited or proofread in any way. It's a first draft of a concept.
It is absolutely not RAW. There is no RAW for UA. UA material consists of conceptual, non binding ideas. Not rules.

The Rules (of DnD) as Written include the PHB, the DMG, the MM, the SCAG, and any other officially released product containing rules.
Everything else is homebrew, and is not part of the RAW (the Rules of DnD as Written).
If it is not official, it is not, and has no, RAW.

You are being overly pedantic. By your reasoning this entire thread is non-sensical since Minotaur horns don't even exist in the 'real' rules.
Your statement that horns are not a weapon is non sensicsl, since horns don't even exist

To even have this discussion we have to assume that the Minotaur UA rules are at least legit enough to discuss...... you are willing to discuss them, but then want to ignore them when your claims are shown inaccurate.
You can't have it both ways.