It's ridiculous. It's not even a 1 out of 10 in terms of inappropriateness, it's fully a 0. It's 100% within the preoperative of anyone frankly to say "hey, can we chat for 10 at lunch?"
Anyone who has difficulty with this should seek a bit of help, and those implying there is something wrong ... they have a different problem entirely, I don't know how to describe it.
My grandparents were born on farms without electricity or plumbing (common for the area), no public healthcare, retirement, social assistance, unemployment, radio, refrigeration, TV, barely any cars. etc.. They were kind and generous people but also resilient and self assured. They literally wouldn't understand the author's concern. It would have to be spelled out to them. They would be empathetic (it's in their character) but wouldn't think anything other than the author has some kind of issue.
Complaining about "Can we chat?" as some kind of 'unreasonable thing' is getting absurd.
People above are commenting 'what kind of stressful world we must live in' - I think the complete opposite: we have reached a threshold of material abundance and prosperity such that the most vague, imperceptible form of nuance in communication is now worthy of demarcation. Only extremely privileged and wealthy people could afford to go on about someone asking them 'if they have time to chat'.