Hi,
I'm pretty sure rollup queries work just like advanced find as we have used them in other custom solutions outside of goals.
Check the 'Record Set for Rollup' option on your goal. If it is set to 'Owned by goal owner' then the results of your rollup query will be additionally filtered to only return records (opportunities) owned by the goal owner.
Rob
MCTS. GAP Consulting Ltd. Microsoft Community Contributor Award 2011 & 2013