I've heard the same, but honestly, with there already being so many trout in the Current River system, I doubt if a few more put in there will make much of a difference, especially cutts, because they tend to be drift feeders that go after bugs. Brown trout would really be the only kind of trout that could be a real threat to hellbenders I would think (and of course browns are already well established in the Current), but I could be wrong. Several hundred thousand rainbows, and about 10 thousand browns are stocked each year into the Current, so I seriously doubt a few thousand more will hurt anything further.
And at Taneycomo, I don't really think hellbenders are even I factor, although I could be wrong.