Theodore doubted that it had been invented with that purpose in mind, especially considering its maker - he hadn't known Slughorn terribly well, but he didn't seem cruel enough to have made the potion with that intent. It seemed very generalized, a way for Death Eaters and the Ministry (once they had become the Ministry) to get away with whatever they wanted or needed, politically speaking. Individual Death Eaters could, of course, abuse that power, if they knew about it. Regardless of whether Blaine had known, though, he had used it against Tracey, which was unforgivable to Theodore.
"You are unbelievably strong," he said to her, touching her cheeks, blotting her tears with his fingers. "He had every card, he had all the power, and you got away. You got away, Tracey." He loved her so much for that, for the reserves of strength she had shown against all odds. "And now that you know, it can't ever happen to you again."