This doesn't seem like a good outcome. I bump that stupid thumbs up by accident far too often, to think that could constitute a contractual agreement is mind boggling.
Should you be allowed to back out of any contract by pretending you didn’t accept when you sent a message of acceptance?
The judge here made the right call and the examples given in the article highlight why this was the correct decision.
In any rate, once old mate sent the thumbs up, they should have exchanged actual contract documents.
This is why contract laws exist and shouldn't be eroded with nonsense like this.
Formalities can help prove things but they are often not required.
I do not know about this situation in particular, though. Reading emojis is like reading tea leaves.