Given the seriousness of the potential injury, it was extremely incompetent - if not, bordering on legally negligent - of the staff not to file an incident report. Certainly, especially if the person who wants to file the incident is petitioning and more than ready to do so. (I can't think of a case where I've been at workplaces where the request to fill an incident report has not been rebuffed).
I hope Ms MM works out OK on the medical tests. I would be following up with the owners of the lounge and the lounge authority with a firm letter / email describing the incident, with a specific emphasis on the lack of attention to the filing of a report and/or the flagrant disregard for the seriousness of the incident. Include a reasonable and suitable request for a directed and timely reply to your satisfaction.
If no response is received and/or the response is not satisfactory / is dismissive, I would consider calling in either the Sydney Airport authority or the relevant State authority / body responsible for workplace health and safety.
I'm not sure if Emirates have a Facebook account with a Wall that can be posted on, but it may be worth posting your terse account of events there. Keep in mind that these Walls are often public and whilst airline Facebook Walls may tend to be "crackpot magnets", it doesn't bar the fact that you can see everything that's posted there. Emirates might deal with your issue with some urgency if they know the wide world can see it; they would be rather folly if they simply deleted your Wall post.
(I am assuming that the lounge in question and the relevant bathroom facilities are owned and operated by Emirates; if it were some third party, I would be going after their throats for a faster response)
By wording stuck doesn't necessarily mean there was any contact. By discussion it would seem as struck would be the more appropriate wording as it does seem to infer there to be a needle handling injury.
Maybe you're right. It still doesn't discount the fact that if someone wants to file an incident report, they should not be denied (under almost all circumstances). Even if there is no injury (or even if it is a "near miss incident"), that is no reason to deny the filing of a report.
To be honest, it may just be that the report may be dismissed after filing (viz. fodder for the proverbial basketball hoop over the garbage bin) - let alone will any action or resolve arise from the report - but it just sounds frivolous to dismiss one from filing a report in the first place (at least in this country).