How can I politely provide factual feedback without "attacking" the style of programming? ... the programmer is pretty young.
in reply to How do you critique another person's code?
Given what you've shown, this seems to me to be as much a behavioral issue as it is a technical one. It looks like a situation where the older developer needs to sit the younger developer down and explain that behavior has consequences, and that coding (and commenting) practices are a behavior. This kind of talk is best done one-on-one, without managers present.
Unfortunately, that opportunity has been missed, and it's now "meeting with managers" time. Given that, I would focus on the technical aspects of the problems with the code and their likely downstream consquences. Avoid making it personal, even if baited.