Remove the restriction. If people can't handle a bit of criticism or others frustration, they have no purpose queuing for the Feast in the first place.
The last thing the team should have thought was acceptable was to remove the only means of coming up with strategy in a team based game.
"Toxic" is an excuse that is used to show one's personal inability to handle the things said to them. Responding negatively and taking things to heart is a choice, believing someone wants you to actually have any of what they have said to you happen is a choice, just like the people who make the comments choose to say them.
People need to choose to not let it get to them and to actually act mature enough to understand that people like that aren't worth their time.
This is not something the development team can fix, whether they choose to re-add chat or keep it disabled. However, the inconveniences caused by such actions has made the mode worse for the vast majority of players who did not act this way or speak in such a manner. Punishing the majority for the actions of the few is simply unacceptable.