Selling ETH is too risky as it is unlikely that it will be dumped afterward, it will most likely bounce and be at a higher price than it is now. It's all speculation, nothing is certain it will happen.
I'd never say it was risky but selling our Ethereum is literally a wrong decision. We haven't any clue yet how this fork will affect the price of ETH but for me, this never has a huge impact on it. The FUDs seem it was spreading making some investors to felt worried about the incoming merge and likely thinking negatively. And this will affect mentally, especially those who still live in doubt about the capability of ETH and beginners.
But anyways, I let people/investors make their decision to sell and also for them to know more about Ethereum.