Quite right. Considerng the legal relationship between MS and ABS, any undisclosed short positions would be considered insider trading.
MS has a two pronged involvement with ABS:
1- Interest in joint venture (long-term partner)
2- Equity interest (indeterminate holding)
Additionaly, it may be accurate, although speculative, to assume the equity share given to MS was initiated by MS to ensure the success of the Joint Venture.
Considering the above, it would appear to be a contradiction in strategy, and legally impossible to short ABS.
ABS
a.b.c. learning centres limited