I've hit the error on both trying to install the assembly and running the CLR once the assembly is loaded and I've switched the Trustworthy property OFF. I've also tried replicating the problem but haven't been able to do so.

i.e. I created a new 2012 DB with Trustworthy ON and a CLR installed. Then did a backup/Restore to a 2014 server. The Trustworthy property is set to OFF and as expected the CLR would not work