Well he chooses the high road. He is correct but the thing is there's no need to use alkaline cleaner if the car hasn't see any rain, mud build up, snow etc. to collect traffic film on the paint.
Also if you are reapplying the sealant every 6 months, traffic film is not going to hurt the paint in that time frame because you have to make the car squeaky clean before sealant application every 6 months. Traffic film needs a longer time to be embedded in.
Besides this menzerna confirmed me that power lock or power protect ultra (eu market, finishing polish with sealant capability) can endure 12+ washes with hard water and strong alkaline car soap. So in the summer, I go with pH neutral if the car didn't see any rain. I use mostly alkaline car soap in the winter.
Personally I strip with dish soap and super degreaser and reapply power lock (if I need light polishing I'll go with power protect ultra). I'm doing this 3 months apart in the winter and 6 months apart in summer. Which is around January-February (1st application of the year, winter maintenance) April-May (2nd, summer prep) October-November (3rd, winter prep). I've seen a great success with protection, cleanliness, ease of care and overall beauty of the car whole year.
Long story short, use the cleaner that suits your cars need. Reapply the sealant when it wears off. If you want to take the harder way he is correct.
FYI: You have to adjust the frequency of applications with waxes. They will wear off much easily, almost one wash with alkaline soap of any kind.