No, i believe we have all read the manual of the UTH and we have all seen the damage they can do if left unregulated. I had the UTH under 2 inches of bedding and it still got up to 110 degrees. if you have everyone in this post telling you the importance of a thermostat then i would think there may be some merit to the claim of needing one. take it or leave it, its up to you.
and just because they are not arboreal snakes doesn't mean they don't need a warm ambient temperature, that statement of yours makes absolutely no sense. they still need a stable ambient temp, not one that get too cold, and by not having anything to heat the ambient air that temp will get too cold unless you have the tank in a warm room (but i believe you said he's in your basement and i can't imagine that being too warm).