I believe that is a flaw with the lint checker (?). The introspection is failing to recognize the return of the decorator and not the function (unless you forgot the @block).
I suspect that too, but I am using Pylint to check for PEP-8 (and plain other typos).
I managed to turn it off by setting this in .pylintrc:
# List of members which are set dynamically and missed by pylint inference
# system, and so shouldn't trigger E0201 when accessed. Python regular
# expressions are accepted.
generated-members=REQUEST,acl_users,aq_parent, convert
Probably have to add the other Block.members later too.