If one were to side with the government, it could be argued that encryption is even more dangerous than guns, because it can be used on a scale that would allow larger numbers of terrorists to organized without the threat of the government being able to track their plans. In that sense, encryption could be argued to lead to more deaths (or at least more horrific ones, see 9/11) than individual gun owners.

To be clear, I am both pro-encryption and "pro-gun". However, spinning the argument to present encryption as a more immediate threat can be done, and quite easily considering the fact that not many people understand it. The argument could even work on pro-gun people!