I used to be quite involved with model rocketry and still talk to people involved with it. Make no mistake - the stuff rocketeers play around with now could take out a substantial aircraft - take a look
here for a bit of evidence of that.
However, for some years all organised rocketry has been NOTAMed, and rightly so. But, I've been to several events where a notamed launch site was overflown directly by both light and transport aeroplanes. I've launched a rocket myself to about 2000ft carrying a hens-egg on a parachute (at a NOTAMed launch) to then be
underflown by a C152. That
would have made for an interesting MOR!
Which is really only to make the point that there are ways and means to ensure that firework launching doesn't endanger aircraft. The PTBs were quite right to presecute this pillock.
G