What could those ribbons even have been awarded for? Brunei hasn’t seen any military action since 1962. I suppose they might have sent troops to assist as U.N. peacekeepers at some point, but you don’t get medals for that afaik.
The Sharia thing is probably a sop to forestall objections to the regime by radical Islamists. It’s one of those countries where citizens get a dividend check from the government instead of a tax bill, so the people are unlikely to rock the boat over rarely-enforced draconian laws.