I think to describe this as innuendo is not entirely fair.
It's all there in public, easy to track down if you want to.
I /really/ don't want to summarise it because without a complete understanding of it I will be unfair to someone. It was big and controversial and resulted in serious schisms in the Gnome dev community. Nat and Miguel's company Ximian was bought by Novell who had a software patent deal with microsoft. There was a lot of trepidation over mono because of microsoft's software patents. Miguel de Icaza founded gnome and had those halos. Ximian employed many prominent gnome developers. My understanding is that mono is now not a dependency of Gnome and there was a reasonable amount of rancour about it.
If I post links I'm tacitly endorsing their analysis - which I don't want to do.
With the knowledge that Nat and Miguel essentially spoke as one from being joint founders of Ximian and there wasn't any dissent from other Ximian/Novell employees, useful search strings might something like:
"gnome mono controversy"
"gnome mono patents"
"redhat gnome mono"
I'd also suggest looking for prominent gnome developers from those days and see what they wrote about it in blogs and mailing lists and so on. I think it's entirely reasonable to check someone's reputation, especially when they advance it. The fact that you can and it might well check out as honest, solid, trustworthy and that they are a person of integrity is really, positive. Please note how careful I am being to refrain from besmirching anyone's reputation here.