Like the other member in the link those look like carriage bolts. I do not see any sign of a weld on the stud the picture. Bolt break inside fix nut or fixed nut breaks the welded that the easiest fix for someone without a welder.
Personally if rust was an issue I would use a nut or two to cover the exposed thread on the bottom and cover the whole whole works with heavy grease. The exposed threads get loaded with rust and even if a bolt breaks loose it locks up once all he rusted thread into the fixed nut.