> If you're a senior developer, you're the one who has to push back against behaviour you don't like. You have the authority.

Not just that, but it seems like the grandparent had issues understanding what they were talking about. This is absolutely fine, and they should have just asked to continue explaining more until the problem was fully understood.

It’s obvious your opinion is important, but it’s not worth a lot if you don’t understand what the actual problem is.

Also, I personally don’t like to appeal to authority (not sure if that is what you meant), and instead just use the Socratic method to keep asking questions until they themselves understand the weaknesses. It’s a very friendly way of doing things.