I tend to think that Satoshi would be fine with it. People can use bitcoin how they see fit without anyone - Satoshi included - telling people not to do so. And retirement accounts are part of the financial system. There has been the ability to have bitcoin in IRAs for years although this seems to be opening the door wider.
Would you trust Bitcoin or crypto assets in your retirement account?
Uh, no. If Satoshi is still alive and saw this question being posed as a serious one, I betcha his eyes would be popping out of his head. I mean, bitcoin was created to be an alternative to the traditional financial system, which includes banks and the governments they're in bed with. One would have to assume that would include the huge institutions that administer retirement accounts.
All of this talk of corporations and governments getting involved with bitcoin makes me shudder.
Is this a smart move or a risky gamble for long-term savings?
Pfft. Unless bitcoin happened to eliminate its historic volatility (or at the very least tamp it down quite a bit), it would be insane to have bitcoin or any other cryptocurrency making up a substantial part of one's 401k or whatever else passes for a retirement account these days. And then there's also that whole 'not your keys, not your coins' maxim. If there's bitcoin in your retirement account, it's probably not actual bitcoin but some kind of derivative--but whatever form it takes, you don't have that bitcoin in your own custody. Again, that's a no-no for those in the know.