I read all the tooltip code from jqueryui and the "open" method is triggered on "mouseover" for each enhanced element. So doing it this way seems not to be problematic (and it honors the timeout etc). 
The "open" method should be called "checkIfThereIsAnTitleTagAndTriggerTheWholeOpenStuffInlcudingTimeoutEtcIfThereIsNotAlreadyAnyOpenTooltip" but I guess that name is way to long ;-)

The only clean way I could think of is to trigger an event each time a new nickname element is added to the DOM. Which can be problematic since there are many different parts where this could happen.