There is an opinion that altcoin should be bought when important news comes out about it, and during this time of the pump the altcoin should be sold.
What do yo mean altcoins should be bought when important news comes out about them? That is explicitly when the pump occurs and you would want to sell them if you want to get some profit. Buying should be on the dip and not the tip. However you may think otherwise.
The second part of your post is also not correct. There is currently a pump occurring in the price of bitcoin and the altcoins are generally showing a dump. This is a good time to buy some altcoins which you previously could not buy due to high price.