not that im on one side or the other but a typical student really doesn't know what's a panic situation and they bolt at the first sign off perceived danger, bolting creates all sorts of problems for instructors and instead of training them properly in a pool first they overweight them and of course do whatever they can to keep them down
Wow! That might be true of really incompetent instructors, but it is wrong in so many ways that I hope it is not common.
It is true that students are often and perhaps usually overweighted. I am sorry it happens, but when it does, it is not to keep them from bolting, because it does not do that. For every pound of extra lead, they have to add about 15 fluid ounces of air, or half a liter, to compensate and become neutrally buoyant. That much extra air makes it harder for them to control their buoyancy, and it makes them easier to bolt.
The better way to keep students from bolting is to teach them ways to handle situations that might prompt them to bolt. That is usually accomplished in the first half hour in the pool.