Tom,
Thanks for your response here.
Any member/s representing more than 5% of total membership (i.e. one person at the moment) can propose a resolution for the AGM. The Board is duty bound to circulate it. However, as special resolutions require notice, they cannot be amended after a discussion at the AGM. The exact text must be put as stated in the notice and will only pass if it receives 75% support. Without the Board's support the chance of a special resolution passing is, frankly, remote.
You need to decide how you want your resolution to be worded. If you actually want it to pass, I think you should take on board people's concerns and reword it.
The Board has suggested a compromise - preventing the Board from unilaterally withdrawing from the Agreement. As already pointed out, any amendment would require WMF approval.
Please let me know your decision ASAP as I need to send out the notice in the next few days.
regards,
Andrew