I don't understand very well the rationale behind the engine change: Turkey was supposed to be an 'easy' win for Hamilton, the most likely result would have been 1- HAM, 2-VER, this is +7 points for Lewis.
Instead, after the penalty, the most likely result is 1-VER, 2-HAM, assuming a team order 'Lewis is faster than you' for Bottas, so it should be -7 points for Hamilton. This is, a net result of -14 points for Lewis due to engine change.
Of course, it could happen that Bottas wins and then it would possibly be 2-VER, 3-HAM, with a net loss of -10 points instead of -14, but lets remember that Bottas has never finished ahead of Max this season, so it doesn't seem an easy task.
Wouldn't it have been wiser to get the penalty at a track where Lewis wasn't expected to win, so the most likely result would be to finish third or fourth instead of second, with a net point loss of -3 or -6 points?
Unless they fear to suffer reliability issues in Turkey, don't see the point in changing the engine when you are expected to win.