Yes, but Gridcomm has intention to expand as a listed company...

Yes, but Gridcomm has intention to expand as a listed company and as far as we know, no Singapore-listed company has offered an MOU for an RTO deal the same as Odin has. Nor does Gridcomm meet requirements for IPO on SGX (maybe someone can correct me on the detail, but there was a post here a couple of months ago on why it was not feasible).
Add to that the looming Financial Crisis in Singapore and an ASX listing makes a lot of sense. There is also no reason that Gridcomm can't continue it's Sales and R&D activities in Singapore as an Aussie listed company.