That of ddennism is a proposal that should be evaluated in deep. As regards I think that it is not so dissimilar from this older idea:
A “two-button system” could have the pro of reducing the time needed to post an observation while, in my opinion, it could be a little be less intuitive then the “pop-up system”.
Regarding the “grey area”, it is true that for certain observations it is debatable if is more correct to flag them as captive/cultivated or not but, fortunately, they are few while the vast majority of them are easily attributed to the class of wild or non-wild organisms.
Moreover, users should be invited to post enough photographic material to enable themselves and the community to make an idea of the wild/non-wild status of a given organism. Unfortunately many users do not understand the importance of photographing the surrounding environment!