Sorry I'm against this idea, if this is some form of fund raising for charity it should be taken to the
Service board or any other board where previous charity have been carried out then it'll get more support and mine too. I'm very sure serious members won't associate with this. This only portray the idea of merit competition which I don't think it is hygienic for the forum. You don't create quality post with the idea of getting merited but as a contribution in regards to quality discussion in the forum, getting merited is just a bonus.
No hate but just imagine this, some random user accepts the challenge he/she now knows all eyes are on his account. what does he do, he takes advantage of that and goes hurting in regards to creating quality content and in return gets merits and ranked up. Then what?, We shouldn't encourage creating quality content just because they want to rank up (receive) merit but because volunteering we want to add value to the forum. If users use ranking up as their main motivation to create quality post, they become liability to the forum when they achieve that goals as the motivation will be lost.
Your answer is very politically correct, but completely incompatible with the reality. Since the introduction of the merit system, users (at least in the rank below Legendary) try to get some of them - probably for most users this is not the meaning of life, but for sure motivates them to make a bigger contribution (and isn't it merit system purpose?).
In the ideal reality you are talking about merit, would only get users: @Mather_Theresa and @St_Francis (who of course would not have wear signatures). But we live in a real world and many users think about merits, is it bad - that they receive an additional incentive to create better (and more) content - NO.
@wwzsocki user has already proven that he can create posts which are worth rewarding - so this challenge can only convince him to spend some more time this week than usual but he will certainly not hurt from writing more posts.