question on presrules

Hi,

according to RFC5025 there could be scenarios where the transformations 
within a matching ruled whose action=block may filter the presence 
document showed to the requestor.

E.g. this can happen when there are two matching rules, one that is 
blocking and the other is allowing, and they have different 
transformation elements. If RFC4745 is applied, the combined action is 
"allow" and the combined transformation is a superset of both 
"transformations".

So, is the assumption that clients are smart enough so they will never 
fall into the above case? or should a presence server prevent clients 
from not doing such combination of rules?

Thanks and regards,
Enrique.