I think, that value is always stored in MC. You can only put your bitcoins into "escrow" (lock them in main-chain) and use "value" on side-chain.
Shouldn't you then believe that the severing of 2-way peg would result in a scBTC value of zero in all cases? I think I've convincingly shown that this would not always be the case. Therefore, a % of the value must actually be stored on the sidechain's ledger.
If 2wp does not work then pegged SC does not work. If we are talking about pegged sidechains then 2wp MUST be working.
or maybe you want to talk about "pegged SC are not possible to create ?" => let's talk about why it is not possible to create functional 2wp SC
SC does not have any value -> until BTC are locked(escrowed) to fund this SC