I see your point, but it makes the problem even worse. Bitcoins coming from anonymous sources like obfuscated Bitcoins from a Coin Join are seen as bad coins already. If virgin coins are banned too, it gets even worse and Bitcoin is definitely not fungible anymore! Are exchanges not discriminating even today by banning anonymous coins from entering the markets? Anyone visiting Binance, Bittrex, Kraken or any other Centralized Exchange today and depositing a Coin Join output will have their assets seized immediately with no rights of ownership for them unless they provide personal documents. If you deposited a transaction from a regular person's wallet however, you would have no issues depositing and withdrawing. The discrimination is already here. While for you one Bitcoin equals one Bitcoin, for centralized institutions and exchanges it does not anymore.
Every single thing you said here are the problems with centralization which bitcoin set out to eliminate not to mitigate. Have we already forgotten why bitcoin was created?
Also we should solve the actual problem where it exist not somewhere else. For example if centralized exchanges are discriminating then we should solve the actual problem by either replacing CEX with DEX or adding more CEX that don't do the same thing maybe in other jurisdictions so that those CEXes that discriminate lose business and lose enough money to either have to shut down or be forced to change their rules.
That also doesn't change anything about bitcoin's fungibility as a currency. 1 bitcoin is always 1 bitcoin whether it is virgin coin, mixed coin or a "regular" coin when you want to use it as a currency not in some centralized service like for trading.
Monero has probably been deemed illegal on less markets and in less countries than Bitcoin.
First of all any country that sees bitcoin as illegal sees all cryptocurrencies as illegal.
Secondly monero's usage and adoption is far less than bitcoin so it should also be less on their radar for discrimination.