I don't think it does imply that. In this situation where (1) "If X, then Y," and (2) "X is not true," it does not necessarily follow that Y is not true.
In other words, X is a sufficient condition, but not a necessary one for Y's truth.
Anyway... not important.
I vehemently disagree. My observation is that the paying DCI audience is (1) alumni, (2) parents/family of current members, and (3) band kids.
In my observation, most alumni (at least those of my "vintage" -- late 90s) couldn't care less that trombones are now legal.
Also, parents/family and band kids have never heard of DCP and are therefore underrepresented in your survey.
In my opinion, DCP has largely become an echo chamber for alumni from the 70s and 80s who are trying to hold on to the "good old days" of drum corps. There are occasionally some good discussions, but on the whole, the posters here tend to completely overestimate the weight of their opinions as measured against the direction of the activity in the whole.
Trombones? I guarantee that parents/families and band kids didn't even know that they weren't legal to start with, and have literally zero opinion about it now.
Also, just for fun... here's a pic of the Madison Scouts trombone section from this weekend's rehearsal: