Definition of "business" aside, their claims about when the work was finished are invalidated by their own messages in the discord chat (dated 10/15)
If they had, in fact, finished it 2 days PRIOR to that then they should not have said it was going to BE done, they should have said it was being finished up or, at the very least, worked on. Or even already finished if they were satisfied with the results and ready to send it on.
Except that.... they did.
The earlier 'will be done' claims were a lie if it was actually completed 2 days before they were approached.
Beyond that, "when do you plan on finishing your part of the collab" is a pretty clear question in my opinion and the response from them seemed to have been a clear "I haven't started it yet, but plan on it eventually."