I think that is normal. When Bitcoin pumps expect that everyone will sell, accept the fact that, that is the truth. We cannot control people not to sell their bitcoins and tell them to wait. We have different situations and problems. Let's all be thankful that all of us are earning and can buy anything we want from Bitcoin.
There is never a time that everyone will sell their Bitcoin holding irrespective of how high price surges. If everyone want to sell at the same time, who will be the buyer? This is not how the market works as everyone have plans for their Bitcoin and how to go about them. Besides, not everyone is a short term investor that will buy and wait for pump in price to sell, some are invested to be held for many years.
The massive withdrawal referenced in this post was by traders, I mean short term investors that are taking their profits as Bitcoin price pumped. It represent a good number of market participants but surely not enough to cause uncontrollably dump in this present market, as you can see from the little to no reaction in the market.