Yes, however neither of those words are complete on the board yet. That’s fine if one of them were in the process of being played, but they’re not. Rapist/racist is in the middle of being played, meaning that the previous turn ended with just “sa” on the board, which is not a valid word.
Assuming rapist/racist is the current turn, then the player who placed sa on the previous turn played an invalid word. It’s possible if the other players didn’t challenge. Sap and sac are both valid words.
You are only allowed to play one direction per turn in Scrabble. It must read left-right or top-down.
you forgot about “ra” and “ist”, but the point is that those three are about to be completed, so all words are correct
“ra” and “ist” are part of the word in process, just being done out of order for creative flair, as you noted. “Sa” on the other hand, is its own thing and isn’t a word. Doesn’t mean it couldn’t be there though as it would have to be challenged to be removed.
https://en.wikipedia.org/wiki/Challenge_(Scrabble)
That said if I had a 6 letter word with that bonus I wouldn’t challenge homey on like 2 points. I’m dumb, but I’m not stupid.