Denying BOD is a mortal sin. I proved that without a doubt.
Being flippant about Sacramental validity is also a serious matter.
I know perfectly well that denying BOD is a grave sin. However for it to be mortal requires a few conditions that you cannot know for certain indeed apply.
I also know that sacramental validity is of primordial importance. It would be a joke to escape the Novos Ordo cult just to end up in another cult.
What of it? Do those true statements change anything about the sinful nature of your actions? Do you think God will think "Oh, he was defending the Truth, so I'll just overlook any sins he committed while doing so"?
Apply your standards to yourself first. You cannot control anyone salvation, the only person you can save is yourself.