I can't claim to know for sure, but that's unlikely because any theater that could run magnetic stereo already had everything they needed for Quintaphonic except the QS decoder. Remember that in 1975, optical Dolby Stereo wasn't really a thing, so theaters equipped for stereo had already sprung for the magnetic "penthouses" (magnetic heads are mounted on top of the projector and read before the picture, which means that you hear a splice before you see it, exactly the opposite of optical tracks), the multichannel amplification, speakers, etc.
As I understand it (i.e., I could be completely wrong), the Quintaphonic setup didn't use track 4 (the mono surround or "effects") channel at all, but it was still recorded on the prints. That allowed theaters that didn't spring for QS to run it as standard 4-track LCRS while the same prints could be run as Quint in theaters that installed QS.
Of course, in that case the audio that was meant to be heard only the surrounds would not have been removed from the front channels, so I'm not sure what that implies as far as what, if anything, was recorded on track 4.
I know at least one of the DVD releases from years back makes mention of Dolby Stereo prints, but I'd have to guess that's either an error or refers to a reissue. Or confusion because the magnetic prints (all? some?) were apparently Dolbyized.
I really need to listen to that again. I enjoy the original Who album and really like the overblown orchestral version and enjoy the movie as a visual overload, but I've honestly just never been a fan of the soundtrack album. I like synthesizers just fine, but they sound out of place to me there and as a standalone audio experience the album just doesn't really work for me.