Trivia: In the opening scene, Mr. Newman told Max, "Please be nice to your sister. Help your mom, and do not touch the drone." During this 90-minute movie, Max's mom Amy says three words ("Winter is coming") and is on-screen less than 10 seconds. Max's sister (not named) does not appear at all. (00:02:03 - 01:02:28)
Trivia: The music teacher, "Mr. K", doesn't have a listing for his full last name. In schools, only the first letter of a teacher's last name may be used when the name is very long (many syllables) and/or difficult to spell or pronounce. However, knowing that there is a "K" [ketamine] or "Special K" and Mr. K incorporated the use of drugs in a middle-school performance and apparently took a "sniff" of something in celebration of his "masterpiece" - the "K" appears to be symbolic. Moreover, the actor playing "Mr. K", Matt Ellis, is known for his voice-overs for (among others) two double-K names: Kotaro Katsura and Kyosuke Karasuma.
Answer: Max's dad probably over-reacted out of anger/rage over the drone and destroyed room and might have made changes after he cooled off. Plus, it was meant to be humorous. A "month in the hole" was immediately imposed; no more birthdays, holidays, summer, etc. would refer to after the month in the hole. Max's dad did not say he couldn't attend school-related events, such as the "Rock of Ages" show. Parents are supposed to give their kids unconditional love. A father can continue to love his son while disliking his behavior. Max's dad may have been unduly harsh (again, out of anger), but he still loves Max - which shouldn't be depressing. I don't think Max's dad said he was grounded for life, just grounded. However, Lucas told his parents that Max was grounded for life - an exaggeration.
KeyZOid
So, even after being grounded for a month, he can't celebrate his birthday or summer vacation?
Not necessarily. Max's dad said those things in the heat of the moment. Although it is possible that Max's dad meant what he said (at least at the time), it isn't probable. The severity of the punishment given to Max was a reflection of how angry Mr. Newman was. A proud and loving father who tells his son "I will always love you..." is more likely to forgive Max so that they can return to their good father/son relationship.