My pet tinfoil-hat theory is that he decided that staying in a French prison is safer for him than being out in the open and get some polonium, or whatnot.
People do that.
Recently, the Bulgarian drug lord nicknamed Brendo not only surrendered, but somehow bribed border control to let him in the country so he can show up directly in front of Sofia Central Prison, with a duffel bag, ready to be taken in. He wanted to skip the bureaucracy and go behind bars ASAP.
This is probably the most ridiculous theory I’ve read all year.
FWIW, France do not extradite its citizen and Pavel Durov is french. He may have been arrested but that doesn't mean he will stay in detention depending on the nature of the charge and his eventual cooperation. Who knows, maybe he called before landing in France so that he was arrested and seen as cooperative.
Why would he get some polonium? There are endless official Russian state telegram channels. Putin clearly has no issue with it or he would have banned it.
Politics is complicated.
[1] https://www.reuters.com/article/us-russia-telegram-ban-idUSK...