Is it a big and obvious scar? I went for Silkair 2 years ago. Silkair is part of the SIA group of companies so I believe the recruitment process is about the same as SQ. I have a mole on my face and the recruitor then told me not to worry about it.
The part where the interviewer took her hand and rubbed off the concealer sounds nasty to me. I mean if she had used concealer to cover the scar, it shouldn't be visible anymore.
I do agree with the "good looking" people on SQ. But hey...beauty is the eyes of the recruitors.