AP at the Washington Post states:
Thai courts are closely identified with the conservative establishment that loathes and fears Thaksin because of his popularity. Court rulings since 2006 have generally served to punish him and his opponents, leading to complaints the rulings serve political aims.
At last the bias of the courts is being seen for what it is. The reporting internationally has been too willing to see the courts as something to do with the rule of law when, in fact, they are about the privilege of the elite and, most recently, overturning elected governments.
This report also makes it clear that:
The amendment under consideration in parliament does not deal with any of the substantive issues in the 2007 constitution, but seeks only to establish a constitutional drafting assembly to begin the process of change.
So, obviously, the bill cannot possibly be anything about the form of government or the monarchy. The whole case at the Constitutional Court against the bill is nothing more than (another) royalist elite attack on the elected government.
While the report points out: “That the court agreed even to hear such a complaint surprised many analysts,” the surprise was that the Constitutional Court was so willing to show its bias so obviously and on a complaint that was so obviously nonsense, suggesting an act of (unnecessary) desperation.