It's worth mentioning again that the shark at Bali's Marine Safari are grey reef shark, as confirmed by the park (TSI's marine department are often always accurate) and physical comparison.
It's simply to attract general guests. Indonesian aquarias, in which BXSea is in my opinion the worse offender, have less focus on what species they bringing in, but more so how to make their Aquarium more marketable and captivating for general guests. Which is why you'll often see things that doesn't look right for most aquariums, like a game corner. It came down to the guests as well, who cares how "cool" the sharks are when taking dark pictures of you with a large fish tank in the background are generally a lot interesting for a majority of people. It's obvious that BXSea attempts to jump on the success of a lot of other aquarias with the addition of these mammals, which also still attract guests at the detriment of the animals.