To me it says that Josh and BB just aren't ready to put a game in Mac Jones' hands even though their K hadn't made an FG that long in ages and they were playing in a downpour. I think they had to balance the value of showing that kind of trust in a Rookie QB, even if he was playing with a veteran's confidence behind a porous offensive line (and an offense that had already turned the ball over at a crucial time), and taking a chance on Folk, which ended up millimeters from being validated. They're just not ready to do that, whether we Monday Morning HC's like it or not.
As for the comparison to "4th and 2," I believe you'd need a truck to remove the memorabilia, which are already in Canton, earned by the Pats' QB in that situation...and we all know how the decision turned out.
The decision is consistent with how they're managing Jones' first season so far. They aren't taking off the training wheels and opening up the playbook so they're sending in plays that minimize the risk of sack fests behind a weak line that could damage the body and/or confidence of a young QB.
It doesn't make for exciting Sunday afternoons, but I think Jones is the real deal and will grow into the role. A half dozen or so wins this year will be a great start for him, without getting sideline by injury when our backup is...who?