It's because that's not a standard private key format.  In fact, I'm not sure what format it's in, because it's 36 bytes, and unless I did something wrong, it does not look like the last 4 bytes are a checksum.   Therefore, Armory interpretted it as a 36-byte integer, which is clearly larger than that 32-byte integer shown there.

I'm not sure what's going on with that key...