No it was the manufacturing of the foam itself that involved Freon. They changed that to a foam that was more environmentally friendly. But, geeze it's not like setting off those big solids could ever be environmentally friendly. If they'd built the shuttle to the original design, with a fly-back booster, there would have been no external tank, thus no foam and also no big solid boosters. Design defects in the boosters (and NASA bureaucrats too stupid to understand the limitations of those boosters) is what caused the first shuttle explosion.
I think if the X-15 had been carried to its logical conclusion, we would have SSTO today. Water under the bridge now. Also NERVA should never have been canceled.