What's the legitimate use case for a 1U rack with 32 cell modems (Assuming 1 modem for every antenna in the photos)?

They are almost definitely either proxy, SMS verification or SMS spam

This is 10000% not to break the cell tower. It is proffessional bot farm for SMS verify (imagine its TIKTOK account, FB account, TWITTER account..)/spamming. They want cell tower up to be able to continue this activities.