An Indonesian spokesperson has stated that MH370 did not pass over Indonesian territory
No, they aren't saying that. They are saying they do not have it on radar and have no evidence that it skirted Indonesia / Sumatra. That's quite a different statement.
Some research into Indonesia radar capabilities leaves me feeling strongly that MH370 could have headed south across Indonesia from IGARI or WMKN or WMKD.
A common theme here - Indonesia seeing nothing; Malaysia radar reports untrustworthy; Thailand unable to hang their had on a 'strange' return - Singapore saying nothing - adds up to an uncomfortable picture for all of them -- MH370 most certainly crossed airspace of one or more yet no one knows where. That's the only 'conspiracy' theory that makes sense and it's simply one of embarrassment.
A route south from near the last known point (hand off to Ho Chi Minh) can't be ruled out at all. Overcomplicating things and relying on radar reports or capabilities that seem to be quite unreliable has caused most to look elsewhere.
IMO the current ping locator search is happening where it is happening based on flight at FL120 on close to due south heading from somewhere on the north east side of Malaysia due to a failed approach, likely all dead on board.
We'll find out soon.