We all know bitcoin runs in a decentralized system, so making it a legal tender simply means the government will also have control over it and it system which wasn't the original motive of it.
No, Bitcoin being a legal tender will still be decentralized, because the Blockchain network is decentralized.Even if bitcoin has been adopted by the governments worldwide as legal tender it will still remain decentralized because that's the nature of the currency.Bitcoin cannot be controlled by any central controlling authority like banks and government because the bitcoin blockchain network has multiple independent processing system called nodes that runs the same blockchain computer programme.Bitcoin blockchain network has been created for financial freedom in it's unique way.So it's impossible for the government to shut down all the nodes in the world,they can only stop the nodes in their country but it still remains pointless because all the nodes outside their country will still work actively for transactions,and if a government wants to stop my transaction it simply means the government will have to stop all the computing nodes worldwide which is impossible.