But if there account setting regarding on "online status" is hidden or unchecked you can't still see if whether he is online or not. If ever na hidden yung online status niya better na puntahan mo yung link ng account niya at kung makita mo na there's no great difference sa Last Active at sa forum time it means he's online AFAIK (just refresh his profile from time to time) and if ever may disparity man sa time that signifies na offline siya. (see the image below)

Thanks dito Baofeng, another kaalaman na naman sa forum.