> And the big problem with commercial deep frying is that the oil is frequently just topped off rather than replaced, so those oxidization byproducts build up over time.

I am sure that cooking (fryer) oil is regularly replaced. Once every few days (max one week) is normal for most restaurants. Also, it is possible to filter the oil in-place that extends its life.

    > polydimethylsiloxane

The Wiki page says this: https://en.wikipedia.org/wiki/Polydimethylsiloxane

    > Safety and environmental considerations: According to Ullmann's Encyclopedia of Industrial Chemistry, no "marked harmful effects on organisms in the environment" have been noted for siloxanes. PDMS is nonbiodegradable, but is absorbed in waste water treatment facilities. Its degradation is catalyzed by various clays.[49] The 2020 re-evaluation of food additive purposed PDMS (E 900) by the European Food Safety Authority found no safety concerns with PDMS in food for its reported use cases, although they did recommend the setting of a maximum limit for potentially toxic cyclopolysiloxanes in E 900 leftover from the manufacturing process.

It seems fine to me.