Needs to be against the rules for this reason.
I think they are already prohibited and the head of officiating is wrong. (I am assuming the written rules are the authority and not the head of officiating.)
Edit:
Illegal Equipment
ARTICLE 7. Illegal equipment includes the following:
a. Equipment worn by a player that could endanger other players.
Appendix E:
A. Details Regarding Illegal Equipment:
6. There may be no projection of metal or other hard surface from a player's person or clothing.
The only way I see that it would be permitted by the rules is if it were soft and non-metal (i.e., no hard surface).