Have you contacted your association management? What do they say?
The permitted uses will depend upon the by-laws, rules and regs of your association. Hopefully, there is cooperation and respect for the rules. If not, the only recourse is a remedy through the legal system.
I might suspect that such use would not be permitted, but it really doesn't matter what I might expect. It matters what the rules are, and if this person is breaking the rules, and next, what support the association provides if there is a violation.
Good Luck and I do empathize with you.
Your board needs to contact an attorney familiar with condominium issues. This owner may be violating your board's rules, regulations, and by-laws. It is possible he could be fined for his actions and if he fails to pay up a lien is placed on his unit and ultimately foreclosed. That's right, foreclose on him and force him out of the building.
Your board must take action, failing to do so could place the board in jeopardy for failing to fulfill its fiduciary responsibilities.
Does your association have legal counsel? Can your wife, as president, call them? You have probably already explored this avenue.
Other than suggest that you explore your remedies through the legal system, there isn't any other suggestion I have. Sorry, I don't seem to be any help. I concurrently shed a smile and a tear for you.
Best of luck........let us know what happens.
When we told him that the other tenants had unanimously agreed that he'd created an unsafe situation in the garage, he responded by attaching a page from his closing statement with the term described in my original question, along with a letter saying that we're all ignorant of what he can and can't do with his "deeded space" and that he'll pursue all "legal and criminal avenues" to fight our decision.
I'm reminded of the following quote from "The Princess Bride":
Inigo Montoya: You keep using that word. I do not think it means what you think it means.