Our keyboard warrior is back!!
Seriously, Mr Tough Guy ..... it's best not to encourage other people to get into fights. While you're excitedly hiding behind a tree watching the fight take place, the OP could get himself seriously hurt if the older son loses face, or resorts to weapons, or returns with his friends.
You're not living in a Steven Seagal fantasy where an obese middle-aged guy beats up everyone -- this is Thailand.