I'm hesitant to reply further in this thread because I get the feeling I've made some people feel attacked and criticized which is not my intent, but I really don't think the issue here is the neurotypical manager's inability to admit they are wrong. Everyone in this conversation is wrong. Everyone believes that both sides of this conversation are having the same conversation, when instead each side is having a different conversation.
To the engineer, they've been asked a specific question "should we rewrite in React?". They assume the manager's has a specific motivation for asking, because the engineer would have a specific motivation for asking, and are asking questions to try to get at that motivation and determine if React will fill the manager's needs. The engineer is having a reasonable conversation.
To the manager, they've asked an open ended question "should we rewrite int React? What are the reasons why and why not? What issues could it address? What are the drawbacks? Any guess on time-frame? Cost?". The question "what issues is the site having that React could address?" is contained in the manager's question. The manager is also having a reasonable conversation.
The breakdown happened when both sides fail to realize that the other person is having a completely different conversation than they are. To the manager turning around and asking them "what issues are you hoping to address with React?" is the same as if someone asked "does this truck have a lot of horsepower?" and I replied "I don't know, how much horsepower does this truck have?" I'm echoing the question back at them. It's confusing and they don't understand why I'm doing it, and it's naturally going to make them feel uncomfortable and agitated. Meanwhile the engineer doesn't understand why they someone is getting agitated over their reasonable fact-finding questions and start getting... well confused and agitated.
In general, I actually blame the manager more for this breakdown in communication, and that's where I'd put the majority of my coaching efforts. After all, probably 95% of a manager's job is communication, and I view understanding how to change your communication to establish a rapport with other people working outside your framework to be part of the job (this kind of breakdown can happen a hundred different ways, it's not just neurotypical vs non). Sadly, most managers never getting any kind of training on this, and many (most?) are abysmal at it.
But the fact is both sides of this conversation failed to understand the conversation the other person was having. No one is "wrong" or everyone is.