I can't explain why the airline are not saying anything, all I know is that a memo was issued to the handling agents staff on Friday last week stateing what I have already said, Air Asia will be leaving STN at the end of Sep and re-locating to LGW.
Often the way to find out a real story is to find out those who don't have an agenda in withholding the info or who have to release it because of legal reasons i.e. redundancy or contract disclosure.
All the facts may not be known but enough of the story is to enable the dots be joined.