Marc,
It's difficult to address your issue from your description. If you read again Martin's explanation, Update is to be used when there is a later iteration on the server. Is that always your case? Or is it just that they want to undo the changes that they made in the workspace. In that case Update cannot take a later iteration from the server. As others suggested in this thread, you can use Add to Workspace to get the latest as long as you uncheck the box as Marc Bower suggested.
I wasn't sure from the thread if you did use Add to Worspace action becuase you keep mentioning update in the embedded browser.
-Celia