Mahler Police Squad is a really good expression! This kind of squads can be found in all genres.
I think that the S/A – A/S question is quite symptomatic when people discuss the “real” intention of a composer. In my opinion the composers often have seen and see this much more pragmatic. For that a nice story I like very much (probably you know it).
The composer and musical scientist Wellesz, who attended the rehearsals for the last Mahler concert (2nd Symphony) in Vienna in 1907, reports this episode according to Fischer’s bio: In the final movement the soprano should sound brightly at “O Tod, du Allbezwinger”. The soloist was Selma Kurz and she had a nice and expressive voice, but not a very loud one. At this point the trombones have to play very pianissimo. Despite of some repetitions the voice remained to weak in order to express what the composer wanted to say. Finally Mahler brought himself to say: “Well, let’s leave the trombones out” and then he added in a nearly festive way: “God bless the conductor, who will perform my scores according to the acoustics of the concert hall."
Fischer adds: Imagine a conductor who would act so today, his condemnation would be sure.
I know, that’s acoustics, not inner dramaturgy as for the S/A question, but it shows, that even Mahler, who worked out and prescribed nearly anything in the score, wanted to make his work “work” and sound at the very first. And if sounds better without trombones - leave them out for this performance.
For me the S/A order has more advantages and more inner symmetry than A/S, but I am sure, that if Mahler had lived another 30, 40 years (as many others, imagine Mahler to live until 1950!), both options had been tried out.
Michael