No one can steal contract value neither transfer it, even the contract owner can't do that. If the owner once wants to get some tokens from the contract he must first pay proper amount of Ethereum to the contract. There is no difference between the contract owner and ordinary purchaser. The smart-contract has no backdoors through which there would be a leakage of nominal value. Smart contract has no pity, no deceit, no greed. It will hold your funds until you claim them.