Spectrum Bootloader Locked?

All boot-loaders are locked (even a Nexus) by default. The question should be is it encrypted so it can't be unlocked and the answer to that question is almost certainly YES.

I doubt it will be encrypted. LG doesn't have a history of doing that.
 
The Revolution isn't encrypted? Interesting.

Nope. Apparently it was coded in a way that made it difficult to load a custom recovery, but nothing was encrypted.

The LG Nitro, the Spectrum's cousin, has already been rooted using preexisting tools, and apparently it was as easy as it could get.