Answers:

What do you think the problem would be if a safe mode were to happen on 19 October?

The answer is that, in safe mode, the HGA is pointed toward Earth and not towards the flux. The right and top sides of Mars Express would then be exposed to the flux, potentially harming the instruments. The solar arrays may be exposed for a short time but would end up edge-on again.

The SAS is needed in the safe mode, as are the thrusters. Without these Mars Express cannot find the Sun or control its attitude. The trouble is that these bits have to stick out to do their job and so there will always be a SAS in the firing line and the only side where the thrusters are not visible is from the top.