Most probably everything within TYPO3 works. Just for security reasons, your Unix Distribution disabled handling of GhostScript files (PDF, AI, etc.) through ImageMagick for security concerns.
Depending on your Distribution, there is a file /etc/ImageMagick-6/policy.xml. This file defines which files are allowed to be processed. If you are "save" or don't care, comment out that PDF is not allowed.
I've the following section in my local setup:
<!-- disable ghostscript format types -->
<policy domain="coder" rights="none" pattern="PS" />
<policy domain="coder" rights="none" pattern="PS2" />
<policy domain="coder" rights="none" pattern="PS3" />
<policy domain="coder" rights="none" pattern="EPS" />
<policy domain="coder" rights="none" pattern="PDF" />
<policy domain="coder" rights="none" pattern="XPS" />
These files are not allowed to be processed. All can contain GhostScript.
Also see:
I'm not an security expert, but would expect that you open an security issue by enabling processing of those files. So maybe make sure who is allowed to upload files containing GhostScript instructions. E.g. limit to trusted backend users.