Cameos of one comic strip character in another's strip can happen for many reasons -- cross-promotion, joint story lines, special events, and mordant commentary.
The latter, I think, is the reason behind Charlie Brown's cameo in the June 20, 2016 installment of Lio. Mark Tatulli's riffed on Peanuts before, always (as I interpret it) to criticize this strip that is continually rerun in newspapers. It's past time to retire Peanuts and give that real estate to a contemporary comic strip. There are plenty of worthy strips that need to be seen.
In this case, Tatulli upends another now overly-familiar Peanuts trope -- the kite eating tree.
It's simple, and it makes the point. On the left side of the panel is the old -- Charlie Brown and the sign. On the right, the new -- Lio and the tree-eating kite. Placement is not accidental. We read from left to right, so moving from Charlie Brown to Lio is seen as a progression.
My takeaway from this panel is this: the kite-eating tree is gone. Can we please move on, now?