Maybe it's worded differently, but from what I read, it mentioned no encryption. If that's the case, almost every phone HTC has released has been with a locked boot loader, this is no exception.
There is a big difference between signed and encrypted, which apparently 99% of blogs don't seem to get.
Unless this is encrypted, it will and should be possible to crack it whenever a few resourceful devs get their hands on the device.
Edit: Nevermind, it does seem to be fully locked down:
Evo 3D CONFIRMED to be fully LOCKED DOWN - xda-developers
Very disappointing. I definitely won't be upgrading right away at least.