I see no clear unequivocal evidence for any "diversion around Indonesia". Subsequent to the loss of transponder signals there are only a couple of Malaysian military radar points over the Malaccan Straights reported, one of which has been subsequently moved, original height data has also been modified (negated). It is also unclear if these are points logged, or a track between them was logged.
No contact was reported on the presumed flight from IGARI across the entire Malay Peninsula.
A ping position (arc?) has been posited for 18:27 broadly consistent with the limited radar data followed by a posited southerly path which only just misses the Indonesian land mass.
Thai and Indonesian radar has not publically reported any contact, they have also not publically confirmed which radar were manned, active or logged - or their range. It is strange that neither saw the plane. If its path was as proposed it would have flown well within 200Nm of both Thai and Indonesian airspace. No word from JORN either.
If there is only confidential (military) information available, its existence (or confirmed absence of contact) should have been reported even if no details were.