@dave247 here is a mental exercise to try (don't do this for real, just do it in your head...)
Go back and read the discussion. Then picture yourself printing it out, and handing it to your CEO for a review of your thinking. Ask him to look over the discussion and give his opinion, not of it UTMs make sense or not, he has no way to know, but of your approach to thinking about them. Would you be happy with him reviewing your "logic" behind spending so much money, spending so much time, and how you are looking to secure your business in the future. Are you confident standing behind your decision making?
Take the reverse. I'm completely comfortable knowing that my statements are public, my boss can (and does) read them, as do my customers. I feel confident that, regardless of if a UTM is correct in any given situation, that my logic, points, consistency, etc. speak for themselves and I stand behind them. I have no worries that someone to whom I answer, even if it is just other peers in the community, can look at this and will agree, perhaps not with my conclusions, but with my statements and logic.
Thinking of it as a private conversation between two people makes it far easier to lose perspective. Thinking about your decisions of this nature as being continuously reviewed by someone to whom you answer can help you step away and look at your logic with an outsiders view and can help force a perspective.
Do you feel that your reasons would hold up if someone whose money was being spent, and whose data was needing to be protected, was the one who was reviewing your logic?