Hate to break it to you, but anything can legally be taken away from you by the justice system. And fighting the government can put you in prison, too.
Usually LARPers are conscious that they don't have magic or any sword skills. I'm pretty sure the person who you respond too really think what he wrote.
Yet the government went out its way to ban bearer shares, bearer bonds, numbered anonymous bank accounts, large denomination currency, anonymous companies, and all the other methods of anonymous banking.
Seems they were having trouble "taking it away by the justice system."
For the same reason government across the world have pressured or banned exchangers of monero.
GP added the "by the justice system" where OP only said "can be taken away". Both digital and fiat currency can be taken away from you through courts, legislation, trickery, or coercion.
Crypto is surrounded by vast amounts of misinformation, misdirection, or misunderstanding. So you get these myths and generalization propagated through lack of education. "I heard crypto is completely anonymous", "I heard crypto can't be taken away from you". Then someone gets tricked out of their crypto, or uses BTC to commit some crime and gets a quick reality check.
If you toss a bag of cash in a hole buried under a grave in Timbuktu, or toss a bitcoin seed phrase in there. Cover it up, leave Timbuktu back to your western country. Then vow to die before giving up the location (you can claim torture or whatever works, but many people in history have decided to be tortured to death without giving up the information). You can be essentially 100% assured it will never be taken. Possible with both fiat and crypto, though you'll be digging a bigger hole to bury an upward amount of dollars, yet crypto is infinitely scalable with the same size hole.
From a black and white viewpoint the possibilities are the same but the practicality is a bit different (then realize with crypto the hole might only exist in your mind). Maybe the government has control over your body but there is some victory in not letting them have your assets even if they take your life and without having to destroy the underlying value.
Personally I think a cleaner distinction is bearer assets vs titled assets. Both can be taken but bearer assets can be made impractically difficult to seize, especially against the masses at once, whereas titled assets (like bank accounts and deeds) can be taken by the government trivially (ex: in US, IRS can freeze without even a warrant) and at mass scale quickly.
Usually LARPers are conscious that they don't have magic or any sword skills. I'm pretty sure the person who you respond too really think what he wrote.