Requirements vs Requests.
For a Rwy 09 requirement (i don't think I've ever seen one but it is possible) instead of a request, coordination still needs to be done between the same parties but it is phrased as a "requirement" instead so there is no need for approval from the parties, it is more of a heads up that this is coming up so be prepared for it.
There are still the same difficulties, getting across Rwy 16 to the holding point. There may be a few aircraft ready at Holding Point Echo, and depending on their number in the Rwy 16 departure sequence - possibly another 5-10 aircraft at Holding point C and B, it could take quite a while to get to the front of that queue to be able to cross Rwy 16.
The Rwy 09 departure will have to be managed through Essendon traffic. If YMML is on Rwy 16 only than YMEN could possibly be on Rwy 17 and the 09 departure would need to be processed through any Rwy 17 arrivals.
Airborne traffic (including YMEN arrivals) has priority over traffic on the ground (including aircraft waiting to depart) so there may be some delay in getting airborne from Rwy 09 but it would be made to work if it was a requirement.
Don't assume that departing Rwy 09 when there's a large queue for Rwy 16 departures will get you away ahead of those departures.