Are you saying a 13 year old is incapable of kicking out a window or incapable of understand that kicking out a window is going to cause catastrophic consequences and therefore should be treated differently?
What about this being a 13 year old is mitigating in your mind vs a middle-aged person?
The kid is arguably too stupid to know better so taping him to a seat and making him look like an idiot is more appropriate (especially considering the parent asked for help in this case) and physical violence is less appropriate relative to an equivalent situation with someone old enough to know better.
Age plays a role up to the point it is practical, kids/teens should be treated more carefully no doubt and in most cases are easier to deal with.
But otherwise this isn’t a punitive thing where we’re measuring how wrong they are and their mental ability / level of guilt before acting. It’s a temporary and immediate solution when the parent can’t handle it on their own and the staff talking to them isn’t mitigating the risk.
The idea is to choose the safest and least violent viable option until law enforcement can handle it (choking someone… eh not so much).
Absent ‘alternative means’ provided by the airline, duct tape is one of the quickest, most widely accessible, and probably most practical if non-violent options all fail. Not everyone carries rope or other restraints. These are civilian airline workers too.
Restraining someone can have a legitimate mental impact and bad PR but so does the rest of the passengers who are all naturally scared of plane crashes.
What about this being a 13 year old is mitigating in your mind vs a middle-aged person?