Most likely it’s an old hodler and he is moving to a new wallet which has better security. As long as they are not sent to an exchange, then I wouldn’t worry. The real worry will be when the MtGox coins move or when those seized coins start to move.
That is a lot of bitcoins, though I doubt they will be sending it to auction any time soon. Most of these bitcoin movements from old, dormant addresses aren't a concern these days especially if there's a good market movement that is happening on the background. You're right, the guy is probably just moving his stuff from one place to another in order to secure it even further. There's still a lot of uptrend potential given the market conditions right now that it's a waste to sell that much coins in today's exchange rate, unless that person is looking to get a mansion somewhere or take the hit and live comfortable for the rest of their lives.
What I think is that whatever is the reason for having transferred those bitcoins to another place , it may be that they have it as they say, better protected, but they also have them to transfer them more quickly to an exchange to make a very good movie We don't know, but these things put people on alert, because they probably want to do something, we are almost in December and it is very logical that there could be a good bitcoin rally, that's what I can think, it's my way of seeing it. The good things of 2023 are comin g, it would be very good but everything indicates that the best is around 2024 or at the end of 2024, and there is still a long way to go , for the most patient there is little left.