It's possible sure, especially if the roots are damaged, or in this case, drowned. But I would expect to see it happen much sooner than 6 weeks. IMO odds are that something else happened to the plants, they were already stressed and susceptible, 6 weeks later to do them in.

Next time cover the plants for frost protection. Water-insulation can work on fruits but not foliage and isn't an effective frost prevention method for young plants. Plus it has more negative side-effects than benefits.

Dave

something else took your plants. If they were frost bit the damage would have shown as soon as the sun hit them.

I think that you watered them too much to keep the frost at bay. You only need to wash the frost off before the sun hits them. It's not the frost that kills them but the sun hitting frozen plants. The cells of a frozen plant burst when heated suddenly by the sun. The water thaws the plant and brings it to just above freezing. By watering the plant and keeping it wet for that length of time you set it up for fungal disease.

Do you use tomato cages? When the plant is small and inside the cage and frost threatens you can cover them with green garbage bags. Just make sure the plant leaves do not touch the bag. Anchor the bags to the ground with soil. Remove the bags in the morning so the plants don't cook and store for the next time.

When watering tomatoes that aren't frozen do not wet the plant. Instead set them in a walled depression and fill ii with water. We always dug a deeper hole than necessary so the plant sat below the level of the ground and left a hole around the plant. When watering we filled that hole with water. saves on water and helps keep fungal diseases away

I'm not sure about that. Frost kills plants without sunlight. Water in plant cells freezes and, when it does, it expands (by about 10%). That ruptures membranes and causes dehydration. I've seen plants killed in an overnight hard freeze when no sun comes out the next day.

I should add that when sunlight melts the frozen water in the cells, the pressure is dramatically decreased. Sunlight isn't going to cause bursting of anything. Of course, it will allow juices to flow freely though the already ruptured cell walls. Frost blankets preserve plants by keeping the temperature above freezing and not by keeping the sunlight off of them.