Yes they are proficient DMs, so am I, so are you. But the reason there's a news item about them is because they are famous and WotC announced they consulted on it. Did WotC announce that Nina Hess worked on the 5e PHB? No. These two didn't even write/edit the DMG, they just did some 'consulting'. They might be great consultants! I don't know. But that's not the point, if the content was why they were hired, then the content would speak for itself. But they chose to give it media exposure...
Let me put it this way: Before 2000 no one cared that Vin Diesel played D&D, almost no one knew Vin Diesel. When he became famous, it was a big thing he played D&D... And I don't care if they are (famous) actors, we had a lawyer here that ran a D&D compatible game company a wrote oodles of D&D compatible books, now he's a judge. I know a great DM that was a politician. People have day jobs, pnp RPGs generally don't pay very well or at all.