I'm not an American, but I'm assuming you're referring to this, right? It seems the administration kept fighting to get railroad workers sick days after that, so that half a year later, the railroad workers got their sick days:

This is a big deal, said Railroad Department Director Al Russo, because the paid-sick-days issue, which nearly caused a nationwide shutdown of freight rail just before Christmas, had consistently been rejected by the carriers. It was not part of last December’s congressionally implemented update of the national collective bargaining agreement between the freight lines and the IBEW and 11 other railroad-related unions.

“We’re thankful that the Biden administration played the long game on sick days and stuck with us for months after Congress imposed our updated national agreement,” Russo said. “Without making a big show of it, Joe Biden and members of his administration in the Transportation and Labor departments have been working continuously to get guaranteed paid sick days for all railroad workers.

This is an interesting point. Optimisticly the administration may have learned from that experience it would be more politically advantagous to support unions rather than oppose them. More cynically and probably more realistically in my opinion, making a stand here is doing a great job whitewashing the administration's track record by going from the next in a long line of union busters to unprecedented PR moves like this along with some real policy strengthening unions. Either way I'm thankful for the development.