Could someone please explain this?
there are two ways you can lose your bitcoins if you try to claim these coins:
1. if they don't have replay protection and you are sending coins to an address you don't control. this problem will be caught fast in the early days if it exists and the first people who will get hurt are the exchanges so they won't even list these coins.
solution: simply move your bitcoin before importing your private keys in the new wallet and trying to claim the coins
2. if you download malware instead of a forked-coin-wallet. something like a keylogger, or something that simply asks you to enter your private keys and then sends them to the attacker!
solution: move your bitcoins first and also never install any of these new wallets on your main system. use sandbox or a live linux or another system whichever you prefer. and always use offline signing the transactions.