Apologising

Hi, parent of 15yo recently diagnosed with autism. High functioning. Yesterday there was a huge meltdown and sadly we had to restrain them as they were trying to attack their younger brother. In the process I was bitten and scratched on my arm, which is pretty nasty looking today. They haven’t angered with us much since then but we have been polite, saying goodnight, hi etc. They haven’t approached us at all to discuss / apologise etc. I know that meltdowns are not deliberate but what I want to know is surely we should be expecting / encouraging / discussing some kind of apology from them for the injuries received? 
They react very defensively to anything that is disagreed with / queried, no matter how quietly and diplomatically. 
Advice welcomed bc life is pretty grim at home right now :(