I doubt they allow an arrested person to use a smartphone, it could cause someone to delete evidence, don't you think?.
It's true that this is "just" a case of tax evasion, but if the authorities have indications that they can find more evidence in Ver's accounts on forums and social networks, I suppose it would be possible.
That's why I said I don't find them appealing, if he had been arrested by the Spanish police for a thing happening in Spain and since it would be just tax evasion , proven by his lack of filling for tax, they might have consented to let him have one, after all whatever he will delete his problem is that he didn't do stuff, not that he did! So deleting doesn't help!
But since he is in for an extradition probably nobody wants an extra headache, so slim chances.
I still think it's somebody from his team accessing it, after all, most guys running a business that posts online are too busy for tweets and others, they have someone writing that for them, of course, unless you're Musk and you like to troll all day.
And since Roger Ver owns Bitcoin.com which has a dozen authors writing stuff I think he might have one trusty guy with control over his social media accounts.
Don't you think theymos would have said something about it publicly?. In case theymos could say it publicly.
Laws in the US about disclosing info during an inquiry are a mess, I'm 101% sure theymos won't say a word!