I agree with you there (CO2 positive pressure). That's why I use the sanitized inverted plastic cups or gallon jugs sometimes in lieu of the airlock (especially if it is fouled up).
I once was short an airlock and plunger, so I improvised and made an aluminum foil "blow off tube."
Even though the ID of this apparatus was at least 2 inches, the krausen was so vigorous (like the pic in the OP), and the foam so dense, that it carried the aluminum foil tube off the carboy.
By the time I discovered it had happened, it was still in high krausen, so I was able to take a sanitized spoon and skim off the krausen that had escaped the carboy, clean the neck and lip with isopropyl alcohol wipes, and switch to the inverted cups.
That's when I decided to switch to a heavier, readily available, and easier to sanitize apparatus (plastic cup or gallon jug) when the situation called for it. I've not had a problem with a blow off tube or airlock popping off since. Plus, I use the anti-foaming agent (Fermcap-S)--which I earnestly recommend to anyone who doesn't have much headspace in the fermenter and/or doesn't have a fermentation fridge. My wife tolerates my brewing, but she definitely appreciates that I'm not as messy anymore.