In consideration of their age, only probation lah............
Use your brain, can or not?
There is no sign to say they broke into the roof-top, because Ah Pin wants to protect his own back-side.
HDB is not public property, because it is leased out to lessees, hence private.
For all you know, the tenants of the block may vote to keep the art-work, because it is relevant and better than the boring
eye-sore of monotonous paint.
The only 'crime' I see is the wording, but that is a social issue. I do not consider it as vandalism. Do you?