Panel 1: As they watch an airplane fly overhead, Gord expresses a desire to be a pilot some day. Brian likes the idea because flying is awesome.
Panel 2: As he and the others wolf down potato chips in order to stab Elly in the heart and twist-twist-TWIST, Mike says that he might write or teach, Lawrence says that he might go into law while Brian reminds us what ethnic stereotype he is by expressing a love of math and science.
Panel 3: He then sets up the punchline and super-stupid and obvious moral by stating that no matter what, they have to clean up the environment. The other three boys agree with this.
Panel 4: As they leave their chip bags on the side of the road like slobs, Brian says that if their generation doesn't do it, who will?
Summary: Any sort of Lynn's Comment would probably reiterate the stupid premise of "How can kids save the world? They won't even clean up their bedrooms!" because the alternative is admitting that Elly brought most of her trouble on herself by turning tidying up into another punishment.
Also, given that her daughter married Lane "Drill, Baby, DRILL!!!" Hadway, there's a sort of conflict of interest here.