I would take some good pics and send them to Bridgestone and ask them what you should do if they explode on the highway... I'm pretty sure you'll get some new...
This certainly possible. My son got four new tyres out of Dunlop but it was a slog. They did not make it make it easy.
They wanted the tyres back so they could examine them, he protested that he could't do that without having to buy new tyres first and who was paying for the postage on the tyres? Overall it took about a year and they only paid part of the cost of the new tyres, they took wear into account, but he did get four new tyres at reduced cost.
Personally, I wouldn't bother. You're probably going to have a fight on your hands as lots of things can cause tyres to crack. Under-inflation, over-inflation, age, chemicals, sunlight, there is quite a big list. You'd have to prove that the tyre was defective.
But you could be lucky. The approach above , asking if they are safe, might well work. There is a chance they might give you money towards new tyres just to shut you up and avoid more potential trouble. It's worth asking.
Personally I'd just change them as I really don't like those tyres anyway. I'd also drive on them. Cracks like that are quite common on older tyres, although maybe not often as pronounced, and they usually do not effect the structure of the tyre.