FPDA dont include east malaysia... why? because the brits,
Aussies, kiwis and singapore are alot smarter then you
think...
and dont think that indonesia is so incompetent that it cannot take
out east malaysia given its resources, manpower and geographical
proximity...
i would be truely be surprised if malaysia could even reinforce its
forces in east malaysia given its present military strength and
troop lift capability across indonesian waters. 
while the indonesians could muster up to ten times the number of
troops on kalimantan then malaysia have currently defending east
malaysia covering a common land border stretching for nearly 1000
km long....
indonesia clearly have the upper
hand...
oh... i read the actual FPDA agreedment too... trust me... east
malaysia aint in it... i dont have the document with me
yet...
the best i could find on the net is this for the moment...
the FPDA only provides for the defence of Singapore and
peninsular Malaysia (it
doesn't include east Malaysia).
http://www.unitedcommonwealth.org/AUKMIN.pdf