Checked back. Alonso only just left the track, but was behind Perez and off the racing line as he locked his brakes and ran wide. Perez did nothing more than take the racing line, which he's entitled to do.
I keep making the point about expected behaviour. Alonso knew where Perez was going, that is the natural line, he chose to hang it out wide and hoped to make the move, he didn't make it, that is cool. He was always prepared for Perez to go out wide, he hoped he'd be in a position to cause Perez to be a bit slower, have just enough room and run alongside him. It didn't work out but he was prepared to go out wide.
Hamilton in Austria and verstappen here had this happen in a completely unexpected part of the corner, for a driver to just keep going and refuse to turn. He didn't take the expected line, the drivers had every chance of not reacting to it because unpredictable racers are dangerous as hell.
Pushed wide on the exit of a corner happens all the time throughout 30 years I've watched F1 races, refusal to turn into a corner and running people off is something that is completely anti racing and no one(except Rosberg) does. Hanging it out late but leaving room is fine but running them right off in an unexpected way just is not at all okay.
In the same way, refusing to brake, throwing it up the inside and locking up(or not) and causing someone to go off track has always been seen as not okay and should you push a driver off to make a move(or go off yourself to make a move) you should give the position back.
He may not have gotten a penalty had he conceded the position.