What do they think the weaknesses of the page are? Do they think rewriting the checkout will solve these problems? How much of the technical tradeoffs do they understand or care about?
To recap:
Is our checkout page not performing well?
Will a new checkout solve our problem?
Why do they think a technology change is a solution?
Do they understand the implications of such a switch?
Otherwise I won't be able to assess if react makes sense or not. It makes sense for some reasons, not for others. If I don't know why they think we should consider it, I can't provide a valuable answer. These are exactly the points you are bringing up as well: I don't know, and I need your input to clarify what we are trying to do.I understand there is a communication problem, but I'm most definitely not refusing to accept I am wrong.
I haven't even stated anything that could be wrong. And because I have fully put the blame on myself, after this particular interaction, the fact that I am able to work perfectly fine at a very strategic level with other stakeholders in my new job shows me that it's not just about me.