For sure Cryptopia will not support the SWAP without paying the required fees. Also they will probably delist MTNC due non-working explorer and too many FORK chain that is currently present.
So you can forget your MTNC in crytopia if possible sell them for BTC if the trading opens atleast you can get something from your MTNC
Cryptopia exchange tend to ask for additional fees to upgrade their wallets when coins have mandatory upgrades. It's their basic approach to earn as much fees from projects as possible. For MTNC after the swap, I don't think that the coin should stick with Cryptopia, that has not actually get their trust back after their hacks months ago.