The Rule 5 Draft was on Dec. 7. It wasn't until Feb. 22 that the Phillies announced he would be able to pitch in 2023.
Unless we hear anything further, it certainly seems like the Red Sox didn't know at the time.
And when exactly have you seen another draftee with his circumstances? The Red Sox knew there could be a waiting period of several years when they drafted him.
I think a bit too much is being made of Song's period of inactivity. He's only 25 and presumably 100% healthy.
Whitlock didn't pitch for 1.5 seasons because of TJ surgery and pitched brilliantly in 2021.
So what happens if the Phillies do put Song on the team, but at some point he really starts to struggle and they decide that's enough? Do they just return him to the Red Sox, no harm, no foul?