a) They are only selling about 5%, so they are not divesting themselves of the vast majority, for now.

b) "Saudi Arabia is pressuring wealthy families to buy in to the initial public offering of its state oil giant, as part of a plan to achieve the $2tn valuation coveted by Crown Prince Mohammed bin Salman... Many of the families targeted had members previously imprisoned in Riyadh’s Ritz Carlton hotel in 2017 and 2018, in what the government billed as a crackdown on corruption. Some of the detainees said they were tortured, according to people aware of the matter. Most were later freed after they reached financial settlements with the state."