The current system table is not able to have a username in it, as which the specified command should run. I even think this is a must, as incron "borrows" its name from cron, which is able to do so. Also it is a must in my opinion as the systemwide directory could (and should) be used with packages, that like to install incron entries in the future.
tag 418852 +upstream thanks this bug has been added in upstream bug tracker cheers,