Some of the point was missed: Why do sticky tires require hard tops or roll bars, when DOT-OE harder tires 100+ do not? Lateral G-Forces!
When sticky tires enable the car to pull more than 1.0 lateral Gs, it is a more likley rollover candidate if it slides. If the tires slide sideways below 1.0g, it is less likley to roll. If you are under 1.0 lateral G, as with most fully-treaded 140+ treadwear tires, you are less likley to roll.
The AutoForm hard top, has indeed proven to provide real rollover protection, vs no top, sport bars, sport hoops, or soft tops. And a true roll bar is just that.
That said, any car sliding sideways off track, (or sliding back on, across a curb edge) can dig into dirt or grass or hook a curb with the sidewall or wheel edge and roll.
[P.S. Anyone loaning tires for track use , esp to a novice, would NOT likely be an attorney! You, your Spouse, and your Heirs would have to sign a LONG waiver.......]