Fair value can sometimes be manipulated by lawyers and/or 'independent' sources valuing the company to be taken over IMO. Worst ulcer I experienced with what I call a 'takeunder' (kinda what you're referring to where minority hodlers get the shaft) was from a Kazakh oil play CHAR.OB (based in US). Lukoil bought out a majority holder of CHAR's stock (Nelson Resources, based in Canada, owned about 60% of CHAR shares I think) so LUK became majority holders of CHAR by buying out Nelson.
Then LUK convinced some other big holders (of CHAR) to go along with a deal to buy out the rest of the shares for less than what was market price before the LUK takeover of Nelson happened. So all the rest of minority holders were offered $5+ per share when the comapny had been trading around $7 before LUK bought Nelson.
There were some minor court hearings for minority holders, but in the end, the big cash and big lawyers of LUK pretty much won out as I recall. LUK hired an 'independent' company to value CHAR shares at the $5+ value so it would look legit. It was a sham IMO. LUK appointed a new CEO to head CHAR and the guy halted new drilling operations almost immediately. Of course, that kind of stuff kept the share price down and the ownership structure didn't allow for a 'white knight' higher offer.
Anyhow, now when I see a deep pocket majority owner of a company I like, I tend to get leary. They usually have to at least be somewhat realistic with a takeover or take private price offer, but they can definitely lowball IMO.
So to answer your question directly about "can they choose to buy back the remaining 10% at a huge discount and screw the shareholder? " I would say not a huge discount, but definitely at a discount.