When you retire the money you have saved for years should make you feel safe. You've worked for years and now it's time to retire to the comfort of your own. Let's face it, risk still exists for cryptocurrencies. For this reason, you may feel like you are alone on a deserted island in the middle of the ocean in a big crypto drop that will occur at retirement time. But even if you lose, you can deposit crypto money for retirement funds in amounts that you will not be upset about. Maybe these crypto money you deposit will cover all your retirement savings in the future. I think risk taking for the pension fund should be avoided.
You are only partly right. All investment funds, including pension funds, do invest in a wide range of assets, from the most solid ones (government bonds and so on) to some riskier ones (like stocks).
The percent of funds in the various assets depends, in some cases even the user has a choice to make (within a rather small range).
This being said, investing some percent of the fund in crypto will not have a dramatic effect, in any direction. Still, if instead of crypto they invest in bitcoin, since those coins will be held for way more than 4 years, they can return nice gains, making the days of the elderly significantly easier/better.
So you are right, they should not take big risks. But some rather small percent has the potential to do more good than bad (especially if the investment is in bitcoin, not the historically disappointing "crypto").