Initially there were talks about the NED train being diverted, but there were some protests from Sedam and other towns and it was scrapped even before it was made an official proposal. Probably the Bidar trains too faced some similar pressure.
Secondly, in the initial days after opening the line, CR cited some PF issues at GR for handling trains on the GR-BIDR route. If I am not wrong, the BIDR line is connected only to PF1 at Gulbarga. This could be a problem for them.