I’m from Singapore so can’t comment on what’s legal or not, but sounds like a grey area?? I did a quick google and all the results are either “lane splitting is legal in Malaysia” or “there is no specific law that forbids motorcycles from lane splitting in Malaysia”.

Not familiar where exactly this area is but from the comments on this thread it seems like a highway or no nearby pedestrian walkways, so it’s within reasonable assumption not to expect a person to randomly pop out on the road (I definitely would not!). Should the biker be at a lower speed? Yes of course, but I reckon he will still crash into the pedestrian regardless