I love commenting on newspaper letter-writers, they almost always miss the point.
This one comments on commercials and their lack of "values," calling them "slips." Which is stupid to say the least. A TV commercial is there to sell the product, it exists to keep the brand name in our minds. The KFC ad is there to make sure that the next time we're hungry we'd consider going to KFC. It is not there to promote any values except eating at KFC.
The goal is to present a memorable scene, in this case done in the form of a joke. There is irony, absurdity, and comedy involved. It's not high art but still a fine piece of writing for its intended purpose. To slam it for not having "values" just misses the point.
To be fair, his comment on the PSBank ad is right. If something is "guaranteed," then it can't be subject to change. Bad writing on the bank's part.