I don't think if it's good to buy altcoins if you just short trade only we don't know if it will decrease more, but for long term I guess this is the right time to buy and hold until the price will recover.
I agree with you on the long-term hold but if you are a speculator, investing now will be a very risky time. I don't think the market will continue to make green candles because the signals are very bad. but I am above all to avoid a lot of losses, we should pause and wait for the market to change to confirm the trend. That is the best way to prevent risks.