It means nothing at all...

If they decide to perform the 51% attack then it will be just for testing reasons because they can't do an economic harm since we are talking about a testnet network. To understand this we must understand the 51% attack and what's the real danger behind it.

Let's say a user send 100 bitcoins to an exchange, sell them and then send the profit to his wallet in a coin like USDT, then he can use the 51% attack to get the 100 btc back just by re-writing the transaction to the explorer and sending those 100 btc to a new address. This is why this can affect the main net but not the test net.