You bring up a good point about the airbags. They go off via X number of sensors being triggered at X levels, one or more of which are in the bumpers.
Hitting hogs can be bad and the Caldwell Sheriff spoke of cars rolling or flipping as a result. So I went on line and looked for stories of cars flipped or rolled by animal strikes. First, there is limited hog crash information in terms of news accounts, though there is a lot of deer accounts in the news. Few hog crash pics, but lots of deer crash pics. Cops, game wardens, wildlife experts, and others all talk about animals flipping or rolling cars, but I could not find a single example of a car being flipped or rolled by a deer strike. This is a subtle but significant point. In every case, the cars that ended up rolling (they all go over laterally, not truck over hood), they rolled after a loss of control of the vehicle AFTER hitting the animal and sometimes without ever actually contacting the animal. The cars appear to lose 4 wheel ground contact stability during the course of some sort of swerve, usually in conjunction with hitting something like a curb or leaving the hard top and transitioning to soft ground, sometimes where there is a dropoff. I found it interesting that there were cases of cars hitting deer and rolling over and the deer strike was to the windshield, a location that would not cause a rollover simply from an impact. The rollover was due to the subsequent loss of control of the vehicle...as sometimes happens with other rollovers not associated with animal dodging or impacts.
I also noticed that by and large, hitting hogs tends to produce damage mostly BELOW the hoods of even smaller cars and much lower on bigger vehicles. Bumpers suffer greatly as do radiators and even sometimes front wheels. Deep impacts tend to be above the bumper on lots of vehicles and often are from the higher grill/hood area and above. The salient points here are that deer, even small deer, have longer legs and tend to bound or leap when they run and this elevates them that much further. Hogs have shorter legs and tend to travel at speed at much lower altitudes than deer and so their locations of impact and damage tend to be lower.
People injured in collisions with hogs tend to have minor or no injuries if the car did not have a subsequent secondary wreck such as hitting another vehicle, fixed object, or rolling. I could not find anyone killed by striking a hog only. People hitting deer often don't have much in the way of injuries either, but because of the hits being higher up, deer come through windshields in quite horrific ways sometimes, resulting in serious injuries and even deaths of car occupants.
Of course there are exceptions, I am sure, but I didn't find any during the 3 or 4 hours I spent Monday reading over dozens of articles and watching online news accounts. I am not saying that hitting a hog (or anything else) can't roll a vehicle directly, only that I could only find accounts where vehicles rolled due to a loss of control either after hitting animals or as a result of swerving with ZERO animal contact. I would not want to hit a hog or deer, but between the two, hitting a hog actually seems safer than hitting a deer, if only because hogs don't tend to come through windshields, probably not even on Echos.