It is perhaps possible that with the broken spokes the wheel could in a spot move close enough to allow the der to touch if it was already compromised with a bent hanger or bent pulleys.
The bike should do fine long term holding your weight and as others have mentioned, your weight has nothing to do with a der failure.
Tandem wheels are not the best thing to go looking for; I've got 2 tandems, one I'm trying to get rid of, and despite both being from the 80s and using freewheels both came equipped with 145mm axles. A modern tandem hub will be too wide, it is largely a waste of time to go looking for something that isn't in your favor to find. For someone your weight I recommend an Shimano XT hub, can use LX but XT is better in my experience. There are other hubs that can be as good but they typically aren't cheaper enough to make them worth bothering with and there are some that are significantly better but their cost is high enough to exceed the price of your bike. Go 36h, 32h will hold your weight if built well with the right rim but 36 will do you better longer. Rims will vary based on disc vs rim brake but the sun Rhyno Lite is a good affordable start. You should have these built but a LBS that knows what its doing.