rocks, I also disagree with your characterization of Mc plus SC's as one seamless ledger in which 21M coins float with sov. If that were the case, why all the fuss and need to firewall them off?
In theory they are buy no one knows for sure in reality.
And again you are simply stating an opinion as if it is fact but not responding to points made before.
The 2-way pegging process merge sidechains into the main chain as a single data structure. At any given time you could look at the bitcoin blockchain and billions of sidechains and see exactly where all 21M coins are in a completely open and transparent manner. That is the definition of a single seamless ledger that preserves the 21M cap and maintains the Sound Money aspect just as today.
It's fine to disagree, but so far you have not presented anything that counters that.