The reason to use mono over dotnet is political. This is stirring up some really old shit; I expect a continuation of that shit now. Mono is currently MIT as is dotnet core. Who knows what direction each project will go now? MS has a history of fucking with licenses and Wine uses copyleft setups.
The Security Online article only cites Margitelli’s post on the matter. My assumption has been the article used the post as its single source. On one hand, watching MS fuck shit up for years, I want to believe Margitelli. On the other hand, researchers using weird tools and uninterested in reality are why curl is now a CNA.
I’m personally frustrated with Margitelli’s post because it’s all about abandoning responsible disclosure globally rather than naming and shaming (Canonical? Red Hat? Both? Others? If it affects all GNU/Linux I’d expect every single distro maintainer to be named and shamed). Responsible disclosure is our best solution to make sure innocent bystanders don’t get caught in the crossfire. When specific entities don’t abide by responsible disclosure we lambast those specific entities not the entire process built to keep users safe.