OK, so I was thinking [rare occasion <_<]about this for a few mins...
Say I have a Command knight out in Face-up defense positon. If I put a Rod of Silence- Kay'est on it, and am able to summon Guardian Kay'est next turn [successful summon], does that allow for an official field lock to occur?
Yes, this combo prevents your opponent from attacking either monster. A similar "lock" occurs with "The Legendary Fisherman", UMI and "Command Knight". See rulings regarding "Command Knight".