Yeah. I can't see Eddard supporting Manderly under those circumstances, but oddly enough I could see him working with Bolton to blunt the teeth in this proposal by preparing and immediate united front against it, forewarned enough to deliver arguments.
It helps that anyone without a smooth brain can tell we wouldn't allow it to pass.
The thing is, Viserys main argument, now private since Bolton made it on his behalf, kind of justifies itself by dint of another religiously concerned faction pointing it out. Other faiths, especially ones with large clout, would demand similar privileges, which could directly effect legal cases the Seven worshippers are involved with.
Why, did Manderly assume that it would not be for some reason? Rhetorical question. Seeing oneself as 'exceptional' in conduct often leads one who is used to being basically an absolute ruler in their personal demesne to be arrogant.
While the fear of Imperial authority and the Throne is fading somewhat, everyone in this room still thinks of it as absolute, going just by the complete silence to follow that staff smashing into solid rock, held by a giant steel dragon.
It must be a startling change, seeing another Viserys Targaryen having that much power over them, the same love of massive parties and extravagance, but y'know, an actual spine to use it and none of the famíly drama.
Granted, Argon V took the Throne AFTER his family drama passed, then went on to manufacture his own... So here's hoping we learn to nip our own in the bud as it presents itself instead of the classic Targaryen tactic of letting it fester as long as humanly possible.