Ugh, you know servers are just computers, right? There are tons of conditions under which a server or the software running on it simply opens a PDF file that someone loads. A CMS's php-based thumbnail generator script alone could do it (especially if made by adobe, lol). I'm just saying, server aren't magic, they're just regular computers and regular computers can leak data outside of Tor very easily. You know how many linux applications and services are capable of using the internet connection on their own? A LOT!!!
btw there's nooooo way in hell it's a hosted machine at a 3rd party host. Almost all web hosts have backdoors to view content on their own servers regardless of security not to mention examining inbound and outbound data to the server. The FBI probably has every host in the US and as many as they could get in the rest of the world examining their data for servers containing files relevant to silkroad or data indicating massive inbound TOR traffic.
The most charitable reading is that you are spreading FUD.
All I'm saying is if you think Tor is a magical cloak of invulnerability that will never ever be vulnerable, you're wrong. Here, let's get you all certified to talk about Tor. It's 3 really simple steps.
1. go to google
2. type in "tor weaknesses"
3. shut the hell up