The zoo med ones don't get hot like the old style ones even unregulated. I would never suggest any heater that gets over 100ºF and I have never found a zoo med to get over 100ºF. it is as safe as a UTH can be.
Even if this is true (I do not have personal experience with them), and I know you are well aware, 100 is still still an unsafe temperature for BPs. "As safe as a UTH can be." is relative and I personally wouldn't trust one without a stat.