First of all it is not explained in-game but your ship facing is irrelevant when your ship doesn’t move, though for the subject that is not important just something of note you might check out.
Even if it meant anything the fact you have to accelerate to 75% speed means it takes time to reach the required speed to warp which means you can be caught, while if you fly 75% speed towards the point you will warp to to escape (pre-aligned) then you hit warp and enter warp immediately.
The higgs rig helps you stay near the roid for a long time thus still can pre-align (both direction and velocity) and escape easily if you are not afk while still stay in mining range for much longer than without the rig.