To my experience footnotes are mostly dependend on any special bars, not only on bars which are near the beginning of a page. So if Dorico will stay by the current behavior there will be the same problems as described here and in other threads. As you suspected - I am not convinced by your example.
Generally, most elements in a score are indeed depending on special rhythmic positions. Hence, in my opinion Dorico should reflect this and treat the rare exceptions as that what they are: exceptions (for example include a flag that shows wether this element should be shuffled by page operations or not). Perhaps it is possible to extend the engrave mode with note dependend text and graphic frames.