If the Constitution says a Con Con may be called by, say, the citizenry mailing a certified letter to their Rep. requesting one and that receipt of 60% of such constituent letters from each district will constitute the triggering event then that is that; there is simply no lawful way to call for a Con Con other than that one method of certified letters.
So if the Con. does not explicitly say that "a nationwide referendum, however non-binding, may be held at the desire of the Executive to request a Con Con" then holding one, or even asking for one, is expressly unConstitutional. You have to follow the one rule as written.
The moment anyone in government proposes a different method, no matter how democratic or fair it may seem, they are by definition acting extra-Constitutionally and may rightfully trigger repercussions from those who uphold the Constitution and consider it the law of the land.
In Zelaya's situation, apparently the Constitution says that any extra-Constitutional action by the executive requires the citizenry to resist.
That is exactly what happened.
Step 1) Zelaya calls for an extra-Constitutional ballot on holding a Con Con rather than going through the proper, Constitutionally-defined, method of doing so.
Note he did not simply call for such a change to be considered via the proper Constitutional method, he demanded the Army act according to his wishes to hold his own self-created system.
Step 2) He was informed by the Army, who had sworn to support the Constitution, that such an action was extra-Constitutional, he was also so informed by the Judiciary AND the popularly elected Legislature.
Step 3) He persisted in his extra-Constitutional attempt and was resisted per the demands of the Constitution.
Step 4) After being removed from office for his extra-Constitutional actions he appealed to outside forces to force his reinstatement and support him in violating his own Constitution.
What part, exactly, makes his actions, not anyone elses reactions or motives, proper from step 1?
That is the first question that must be answered before he can be rationally or properly defended.