Miso should certainly have paid him the bonus because at the point when the bonus was due, he was an employee. It doesn't matter that he did not claim the bonus

Miso should certainly have paid him the bonus because at the point when the bonus was due, he was an employee. It doesn't matter that he did not claim the bonus (it's the company's obligation to pay him, and since it was not paid, it should now be paid with interest) or there was no written contract (email and/or verbal communications are contractually valid). Having said that, I don't think it is correct to name and shame the company this way because it damages the reputation of the firm, and thus making it more difficult to claim the bonus. I'd have hired a lawyer and settle with the company (i.e., claim the bonus and legal expenses) if I were him.