In contrast to its name, the Tiberium trooper is not detectable by this power.
While the Scrin are known to be Tiberium-based lifeforms, only a few Scrin units are able to be scanned. Furthermore, even Scrin units who have visible Tiberium crystals on their body like Shard Walkers and Ravagers are not revealed. This is most likely done for balancing purposes.