Problem: Walk into a bar, pay for a drink, BTC vanishes into thin air because the node was spoofed or you got MITMd.
What problem? Nobody can steal a customer's money that way. The bar won't give the customer an address that the bar doesn't control, and the customer won't sign a transaction to any other address than the one he receives from the bar. Are you worried that customers will double spend against the bar? If so, it'll quickly be discovered by the bar.
That's not the worry. A man-in-the-middle attack (MITM) means that what the bar thinks is a valid node to the rest of the bitcoin network is actually the perpetrator.
That's the scenario we're talking about here - validating the pathway between user <--> node.
I want the validation to remain trustless and to not require any external validation e.g. "I say my node is valid and here's my driver's license to prove it." - validation should be like the rest of bitcoin: trustless and distributed, built upon a cryptographically signed 'proof-of-x' function.