So trade your eth for btc and withdraw ASAP.
He isn't likely to do that, since Yobit's fee for bitcoin withdrawal is something like 0.0012
BTC, and it's always been that high.
My guess is that the ETH wallet is just temporarily in maintenance mode, since that's one of the most popular coins to trade there. Most of the shitcoins on Yobit have wallets that are in permanent maintenance mode, which I learned when trying to buy some RDD a while back. I still have some on Yobit that I can't withdraw and can't trade because the amount is too small. They really should delist about 75% of the coins they offer since you can't withdraw them.