As subject says, would be nice is the program monitored the clipboard for magnet links and opened the program when one is copied to the clipboard.

Thanks.

If you copied the magnet link (or just the hash), you can just switch to Tixati and press Ctrl+V. (Continuous clipboard monitoring is generally not a safe behavior.)
Magnet link association is also available in the Settings -> Shell Integration menu.

Continuous clipboard monitoring is generally not a safe behavior.