Thank you for your question.
I am Dr. Su S. and I will try my best to help you.
Rubbing alcohol can have deleterious effect.
In small doses it can cause irritation of the mucus membrane of stomach.
In large doses it can cause CNS depression, dizziness, flushing, fall of blood pressure etc. It can become a medical emergency.
When he took a sips only and has spit it out, it should not cause much effect.
Still, I would advise you to call local poison center at(###) ###-####
If he develops any symptom, then you should consult ER.
I hope this information will be helpful.
If you have any query, please feel free to ask.
If you are happy with my answer please click on the Excellent/Good rating.
Wish his healthy life.