I agree with both of you. His changes make sense, and he is correct on most of his statements. However, that doesn’t necessarily merit the code change.
I also get annoyed when a developer adds a variable or function in the middle of a class or project using a completely different set of coding standards than the rest of the project. I found a few functions in a C# project the other day that were named with the classic Java camelCase() style. Ick.
Unless you work a some type of ultra-strict software development company that demands that your tabs be saved as spaces, and that a tab is 2 spaces (so more code can fit on the screen), I would stick to the overall rule that the original code designer picks the coding guidelines for that file or project. Everyone coming in after that must follow (to the best of his/her ability) the same guidelines. The coding standards can be changed only if the code is “given” to another developer due to the original developer leaving the company or the team.
Or, you can just refuse to work with anyone else 
- Mr Jackson