Retirement accounts have to passively invest, but not in S&P500 specifically I think. I'm sure there will be passive funds that don't adapt the rules change.
edit: Google informs me that you can change the stock allocation in your 401k at any time.
Oh, I wasn't sure if you were referring to the X link in the original post.
Yeah I don't know what's going on, they banned me for being a spambot or something. Then they unbanned me again, I got the email, but the site hasn't caught on it seems. If it's still banned in a few days I'm gonna remind them about the DSA again. Technical issues are not an excuse to get out from legal obligations.
edit: Google informs me that you can change the stock allocation in your 401k at any time.