Resource is there but I don't know what's taking WCR this long to run a MEMU on ET-BPL section. Can be easily done by Rake sharing. The LHB MEMU rake stabled at ET can be used on BPL-BINA section and the current rake for BPL-BINA can be used in ET-BPL section. Even the old non 3-phase WR marked BPL-BINA memu rake is still parked at NSZ eating dust that can be used as well.
As for extension that will not work as It has early departure from BPL and it being coming from ET will lead to even more odd departure time from ET which is not beneficial for updowners.