Yes, you are right: The question is really how can LTC-x coinholders be protected from the dumping that is possible from cloning LTCs of the main fork.

Let's say the fork is on 5th April 16:00 GMT.

1. On April 5, 15:00 GMT, I go on cryptsy, sell 10 BTC for 400 LTCs, send the 400 LTCs to my wallet.

2. 16:00 GMT- => Fork happens using the blockchain info up to that point.

3. On 17:00 GMT I send my 400 LTCs back to cryptsy and sell them for 10 BTCs. So I have my 10 BTCs back.

4. I now have 400 LTCs on the LTC-x fork which I'm ready to dump whenever it hits an exchange.

This is too exploitable.