As long as you would be selling them as model rocket motors, what difference does it make if it is Joe Hobbybuilder or XYZ Firewurx Corp. buying them ?
Nobody mentioned actually marketing them as 'fireworks'; I think that is the key here.
On the show "Mythbusters" they use OBVIOUS Estes model rocket motors often in ridiculous stunts/applications that are violations of the model rocket safety code .
"Off Label" usages of products happens all the time.
I do however think it would be EXTREMELY FOOLISH to actually market them to firework companies; then you WOULD be implicit in the usage.

Then again, I would like to see ALL regulations of both consumer AND display fireworks removed as well.
I'd like it to go back to the way it was in the 60's prior to the ban on M80's, cherry bombs, silver salutes, and blockbusters.
Those can ALL be used safely and correctly.
Idiots holding them that had fingers blown off ruined it for the rest of us that have actual humanoid I.Q.'s.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !