On the lag spike thing, I thought of that - there are a ton of games and servers (not necessarily on KF) that kick for latency. Spiking above a certain number like, say, 200 for about half a minute will disconnect you with an auto message giving the reason. It's nearly a standard server add-on in Battlefield 2 because people from all over the world play, and lag/hitboxes can get very bad there.
Also if you've noticed.. ZED time changes your ping it seems. Simply disabling ZED time, or making the mutator a tiny bit more complex to only check latency when slo-mo isn't on would work fine.