Handshake agreements have been a thing for a long time, but this is an interesting take. The article doesn't go in to depth on the ruling but I'm sure the conversation was more than.

"Hey pay me 1 million loonies" (Thumbs up)

There's likely context that led to the conclusion it was accepting a deal. Because a signature doesn't even always make a contract valid. It has to be a meeting of the minds as well.