He is full of it!
Silicone oils or fluids have been used for years to create water repellant surfaces, are anti-corossive,and ease application of waxes or such.
These silicone oils are a problem for bodyshops as they are very migratory and evaporative, and if not totally removed before a bodyshop attempts sanding and repainting a condition known as "fisheyes" will be created in the applied paints.
The use of "siloxane" resins, a member of the silicone family (to keep it simple) are not migratory, nor highly evaporative, as a result some of these, such as aminofunctional's, polyaminosiloxanes are found in the composistion of todays automotive paint systems.
Most of todays quality waxes and sealants no longer use the old silicone oils, which are less expensive than siloxanes, however the grade of them chosen may affect long term protection and evaporation rates.
As far as his statement that they attact UV rays, it is the opposite, as they produce a "gloss" or shine, which "reflects" the UV rays from the surface, which reduces their opportunity to penetrate into the vehicle's paint film build and attack the film formers/binders of the paint film.
A siloxane resin will provide the same gloss/shine, but since it is not as evaporative and can withstand higher temperatures than a silicone, they provide improved protection.
The industry refers to these siloxanes as amino functional resins.
I would suggest that your bodyshop spend a little time doing some real research, talk to I-CAR, etc before passing out such mis-information.
By the way, among my many abilities, I painted my first vehicle back in the 50's and still paint vehicles and such today, plus before I retired, worked on a daily basis with Ford, GM and Chrysler's body and paint tech centers, as well as paint engineers for PPG, DuPont, BASF and Sherwin-Williams, worked with I-CAR on various paint and corossion concerns, etc as Director of Sales and Technical Services for Automotive International, Inc.
Grumpy