I may be way off base here, but I think the tech doesn't know what he's talking about. If anything, the aerator will help eliminate stratification by moving the water in the water column from where the aerator is located to the surface. That's one of the reasons why the aerator is in the pond, to help destratify the water.
The only thing that could throw a curve into it is if the aerator was in the deepest part of the pond, on the bottom.
If I'm wrong here, someone let me know and I'll delete the post.
