The message below was the response I received from Red Gate support:
I am currently discussing with the developers about the change to having strong name signed assemblies for certain protections as it is very over-restrictive (there are plenty of situations where you can not strong name sign an assembly because of trust setting which could prevent you loading dependencies). The change was added to improve security as one of the developers working in a different part of Red Gate came up with a potential attack vector on the protection methods that used compression. As all a potential hacker could do was get at the uncompressed, but still fully encrypted data, it was not a major issue but one that needed to fixed. Hopefully we should be able to provide a better way of protection if you aren't able to strong name signing.
Darn developers... always think they know what's best.