I read some discussions that those old bitcoin movements can create fear on the market. People think those old bitcoins can be dumped on the market and will cause a price fall.
Actually it is. Imagine someone hybernate for a long time and a massive bitcoin amount is suddenly will be send to an exchange like 10k bitcoin, of course this will make everyone worried. Somehow those old bitcoin users are probably selling it especially if they are just a normal people and dont associated with trading itself. They can also talk to exchanges for otc deals instead to avoid being dumped on instead.