lemaysa, give us the whole story please. LIke you could be possibly forgetting some details as to in which context he spat.
Say like for example, the child was wearing a tzilim around his neck and wouldn’t take it off in shul , esp. during an aliyah.
Or if the child was spitting first and this was a way of teaching him how it feels to get spit on.
Or say the chasid was choking in a restaurant and while trying to dislodge the calzone with cheese and brocoli from his tonsils he accidentally spat on the kid.