Brazing is the easiest and best way to repair cast iron when high heat during use isn't an issue. Pretty much zero chance of it cracking. No preheat. No postheat. No short welds. No peening. It just works.
The lack of tensile strength is not an issue most of the time. Only when the parent material is very high strength (not all "cast iron" is created equal) and actually sees that type of load in use.
So many people think that brazing is not as strong as steel. One of our many assignments I did in school was to braze steel parts together then put them through a guided bend tests and tensile pull tests. If the brazing and prep were done correctly, the steel fractured and the brazed filler material held. I'm not saying that will be the case with high strength alloys, but with mild steel it is.