Stelios can appoint who ever he wants however as the bearded one showed when Virgin was a PLC there are strings attached in being a PLC and coming back in and effectively taking over while a minority shareholder has a cost.
The public way of getting rid of Easyjet board members and refusing to sign accounts undermines the professional management brought it to run the company.
This means the next set of management end up being Yes men who work to the whim of the largest shareholder than for the company as a whole and you ultimately end up undermining the whole company.
Entrepreneurs are like great football managers and players, when you leave a successful club you are best not returning to it as you may end up tarnishing the original reputation.
IF Stelios wants total control then let him take the company private and buy out the shareholders BUT in undermining the people actually running it you damage the company. At some point in time the other shareholders will decide that a single shareholding block has too much power and when that happens in a PLC you get a total block where decision paralyis takes hold.