For the same reason spoken languages often have semantic structures that make a literal translation often cumbersome and incorrect, translating nontrivial code from one language into another without being a near expert in both langauges, as well as being an expert in the project in question, can lead to differences in behaviour varying from “it crashes and takes down the OS with it”, to “it performs worse”.
They’re not trivializing, just noting that the different things you need to discuss for kernel development compared with other work. It is very different in a lot of ways, and does shape your perspective. I also find it interesting.