As far as I know, the electric loco was not shunting at all, not even in the reverse mode. It was just attached along with the entire rake. That's how trains from SRC yard generally get shunted to HWH (& also get shunted back from HWH to SRC yard).
The shunting duty is generally done by KGP based ALCos or EMDs, which always get connected at the front of the rake.