As usual with these scenarios, we need more information. But lacking it, I’d say the dad acted badly. Not sure it is sufficient reason for mom to leave, but sure the basis for major disagreement.
Yeah, the kid’s behavior is serious and needs to be addressed in a meaningful manner. But once you get the cops involved, you lose any control you might have had over the situation. Add in the often (IMO) draconian drug laws, and a parent could end up with their kid facing repercussions far greater than the parent thought appropriate.
Sure, the kid shouldn’t have pushed the dad over the chair. And that would make my blood boil. But let’s be serious - this isn’t the first time a kid or parent touched each other in anger. When I was a teen, my dad slugged me, and I told him if he did it again I would kick his ass. (Definitely not our finest moment.) I dunno, but that doesn’t impress me as all that much different than the OP. Should I have called the cops on my dad? Or should he have called them on me for the threat? (This was probably the only time he hit me - other than spankings at an earlier age.)
Here there’s no premeditation, no apparent injuries, and no aggravation - i.e., the kid didn’t kick dad once he was on the floor. So yeah, that is a second VERY SERIOUS thing the parent would need to figure out how to deal with. But I’m not sure it necessarily requires police intervention. What has he been like before? Grades? Attitude? Interests? Helping around the house? Job/activities? What are his friends like? What are his future plans?
Another thing, the parent could always call the cops at a later time - after the parents had time to think and talk it over, and hopefully discuss it with the kid. When you say the dad told the cops where to find the kid, does that mean the kid was caught with drugs? And that that was the dad’s intention?
Now what is the dad’s participation in any prosecution going to be? Is he going to be the complaining witness, or is he going to pony up for the defense costs? If my kid had been relatively decent for 16 years, I would hope I would look at this as an opportunity to teach him a lesson and mold his behavior/personality, instead of seeking a way to punish him in a manner that would have lifelong repercussions. A conviction could definitely preclude him from opportunities in the future. And while it is possible that the kid could repent and the family draw closer after legal proceedings, I suspect that would be a FAR more likely result if the family handled it otherwise.
As seriously as drug trafficking is often treated, I would be EXTREMELY hesitant to have my kid burdened with such a charge at such a young age for what sounds like a first infraction. I think it would be far better to wait for the kid to return home (I presume he is not sufficiently independent that he can simply never return?) The parent can certainly insist on “Not in my house.” Andif the kid doesn’t like it, they can investigate what it takes for him to be legally emancipated. But I would like to do whatever I could to see what we COULD do ourselves, before I turned it over to the authorities.
Final observation - while I would not want my kids dealing out of my house, my response is likely influenced by the fact that I strongly disagree with current pot laws.