Which ultra sonic do you think made the sound worse, David?
I've never had any problems with LAST treated albums I've bought. They have a little less groove noise.
As to the topic... That guy is mostly full of ****. The whole vinyl cleaning with specific additive to the water, and the sonic cleaning machines have been thoroughly vetted. He's counting on your ignorance towards all the research. And he's using misinformation. For example if you use dish soap it leaves a residue, and so does surfactants made for photo development. None of that is true with a pure surfactant. Multiple chemists have weighed in on the topic. There is complete safety in using different anti-fungal/bacterias, iso alcohol at certain percentages, and surfactants. This has been verified not only chemically, but with microscopes.
The one thing he's very correct about is that fan drying is not ideal. A lot of debris, while loose, can still be left on the vinyl. But where he's very wrong again is that you shouldn't vacuum them when you're done. You vacuum dry them but you apply more distilled water with surfactant when you do it, so that the debris will be in a solution as the suction occurs. Vacuuming is 100% safe, and has been the preferred method by multiple places that archive vinyl. While the all in one machines are much better than all previous solutions, the vacuuming is an improvement, and the machines that can use a specific solution are superior as well.
Comparisons have also been done between different frequencies. The debate on that is still out there slightly, but most people think 40khz is great. This guy might be onto something that 35khz could be slightly better. I don't know about the angle, because, it needs to hit it from both sides... that part makes little sense.