He did shut down the strike yes, but was recently credited by the unions for helping them in the months since to apply pressure to finally get them the sick days they were after.

Quote from the article:

"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.

That’s not even mentioning all the good things happening at his NLRB under Lina Khan. My favorite of which being the new rule that straight up just orders companies found to have engaged in union busting tactics in response to workers trying to get a union election to immediately recognize and begin bargaining with said union.