what are my options in protecting myself from physical attacks?
The first rule of protecting yourself from physical attack is not to tell people about your cryptocurrency holding but since the transaction involves you and another party which I believe a big amount is involved I hope the person is someone secretive. In the meantime, I will advise you split the BTC into 3-4 different wallets.
Technically, don't receive the payment direct to the Ledger wallet you bought because it will be easy for an attack to know your wallet and like others have said the only way to keep your transaction is through a crypto mixer site but you can also make use of privacy coin like Monero.
transfer the bitcoin to another wallet, letting others believe that I am not the holder of those bitcoins anymore?
Yes, this is the best option and you can move the BTC little by little with the use of a reputable crypto mixing site.
Be careful about the crypto tumbler you recommend there has been an issue where a good crypto mixing site turns out to be scam years after but Chipmixer seems to keep a good record than other mixing sites.