"The buyer, Kent Mickleborough, later spoke with Swift Current farmer Chris Achter on the phone and texted a picture of a contract to deliver the flax in November, adding 'please confirm flax contract.'"
If I've talked to you on the phone about the contract and then send the image with a request to confirm the flax contract, it's harder to argue that a thumbs-up only reflects receipt of the message instead of a confirmation, especially if no further response is sent by the recipient.
I can see how the buyer might interpret it as acceptance, but it’s such a vague response that it was irresponsible not to follow up, and I can’t help but disagree with the decision in this case.
What’s the point of the contract section where the signature goes? It’s there to remove ambiguity surely?
This is the key. It's a pity there isn't a widely accepted standard here. A 'friendly acknowledge' and an 'I accept'.
That said, this is why contracts exists.