I don't believe Mr.T's "Releaser" is a Radiant at all. At most I think she might have the Releaser Honorblade.
If memory serves I think it was in WoK that we get the snippet from the Diagram were Mr.T knows the Honorblades are with the Shin and that they might be used to create a Truthless.
My current belief is that if Mr.Ts "Releaser" can surgebind it is because of one of the Honorblades used to forge Szeth. I had actually considered that Malata might not even have an Honorblade and be a complete decoy because they could possibly avoid a demonstration under the excuse that the Releaser surges are too dangerous, but all Dalinar has to do is ask her to inhale Stormlight. For that matter, does Dalinar know that Radiants can make their spren change into any weapon? That's a perfect Radiant confirming check.
I actually expect Mr.T to have at least two Honorblades in his company, since it was mentioned that he specifically wanted to hide Adrotagia from Szeth, and I expect he would want a second way back, if necessary. Her having an Honorblade seems the most likely reason to me. By presenting Malata as a Releaser she instantly becomes the biggest threat and draws the focus away from who I think the real powerhouse is.