So they tried to "overthrow the government" by filing a petition to call for early elections? That's quite a stretch...
Petitioning for early elections (even if impossible legally) is a far, far cry from "overthrowing the government"*.
Would you be willing to edit your original post to provide some context here?
In this case the MoU was not petitioning the House to call an early election, it was petitioning the Senate and Governor General to call an early election, who do not have the legal authority to call an election while the government has the confidence of the House.
And whether it's conditional on your demands being met is irrelevant. You can't hold a gun to someone's head and tell them to do something, and then say "well I was only going to fire if they didn't do it". The problem is in the threat, not the ask.
As far as the petition for an early election goes, I agree I can't find it in the MoU. Perhaps it was reading between the lines and combining statements made outside the MoU with what was found within.