In the U.K. that would be an arrestable offence 1. For causing harassment, alarm or distress 2. common assault and 3. Criminal damage to clean up his clothing and hair etc.
I don’t think this kind of protest is justified, but then again I am not living in Pakistan and not witness to the struggles faced by ordinary Pakistanis.
On dawn it said that it was believed “someone paid this man to throw ink”. Whatever is the case, your Foreign Minister should sack his head of security.
Clearly this was a failure of security.