Not 100% sure, but it depends on the situation I'd say. For example, did the Witch know who Mafia was? If it is, how you say it was then -
Start Day X -> Town, GF, Mafioso/Random Mafia, Jester, Witch.
Start Day X + 1 (GF Witched into Mafioso/RM) -> Town, GF, Jester, Witch.
Start Day X + 2 (GF witched into Jester) -> Town, GF, Witch.
Start Day X + 3 (GF and Witch vote Townie) -> GF, Witch.
If Witch didn't know Mafia and Mafia doesn't know witch, and had already lost scum-shield, Controlling the GF twice isn't a bad call - it prevents them attacking you. It isn't ideal though for the Mafia.
Although, if the witch knew both Mafia and Mafia knew witch it could be potentially seen that way.
It's a complicated issue for sure. Also you have to remember Witch wins if Town loses, not if Mafia wins. While Town losing and Mafia winning is a common outcome in ranked, it is possible for (and I personally have had) a Witch only win.
TL;DR
I'd say it depends on the circumstances of the match and how things are knowledge wise for Witch and Mafia, as they may not intentionally be trying to lose the game.