That explanation offered just doesn't make sense to me. Fine, if x of the 7 cameras are obscured, just say x of the cameras are obscured, and then delay the decision and find one of the plethora of cameras that aren't obscured, and base it on that.
It's a shockingly bad decision.
I think the first para of The Guardian match review captures it well:
How heartening after three months of lockdown, death and strife to have something so trivial to argue over as a disallowed goal in a 0-0 draw. Welcome back, Premier League.