a bit more coherence

i thought the description of coherent access sounded sensible, so i tried it out. but here's a weirdness (from a certain perspective, anyway). let's say X creates a private node. then, he gives editing rights to Y. well, in the default edit interface, Y can go straight in and use the same coherent access input area to offer access to Z, even though X didn't intend to give access to Z. (imagine: X trusts Y but not Z, but Y trusts Z. so, only Z is malicious--but as author of the node, shouldn't X be given say in the matter?)

is this really how it should be?