It feels like there’s some confusion over the overloaded term “bandwidth” here. The bandwidth limit in place of the symbol rate is 2.8 kHz. As in, you can use any symbol rate you like as long as your emissions do not exceed 2.8 kHz of space in the band when measured from the 3 dB mark.

I feel like the intended use of the word “broadband” in this context was the more commonplace (but imprecise) “data rate” definition.