If it is on the internet and not restricted, it will be found. It may make it harder to find, but it is still possible a crawler may happen across it.
What is the link so I can check? ;)
If you have outbound links on this "isolated" page then your page will probably show up as a referrer in the logs of the linked-to page. Depending on how much the owners of the linked-to page track their stats, then they may find your page.
I've seen httpd log files turn up in Google searches. This in turn may lead others to find your page, including crawlers and other robots.
The easiest solution might be to password protect the page?
No, there's still a chance your page can be found by search engine crawlers. For example, it's been speculated that data from the Google Toolbar can be used to alert Googlebot to the presence of a page. And there's still a chance others might link to your page from external sites if the URL becomes known.
Your best bet is to add a robots meta tag to your page, this will prevent it from being indexed, and prevent crawlers from following any links:
<meta name="robots" content="noindex,nofollow" />
why do you think that when you have outbound links PR is gone?