The number of extra trains per day via Bendigo would not be many and with 60 minute off peak passenger frequency it is possible to punch trains through especially on the Up hard on the heels of Up passes ex Bendigo. On Down with MT trains faster speed so probably easier to get through between the hourly passes.
BUT only talking about 4 - 6 extra tarins a day mainly in evenings or overnight so potentially no big deal. As others have suggested may work better as Ultima Intermodal via Bendigo overnight both ways, otherwise Down MT grains via Bendigo, Up loaded via Dunolly .
Any stuff up on the bg lines or on the dg stction and the whole thing will grind to a halt, with Inglewood - Eaglehawk re-opened you have a b safety valve in case of trouble South of Inglewood.
The main thing is the half completed MB job with the bumper grain harvest and all trains going down a dg bottlekneck between Dunolly and Maryborough coupled with the long single line sections (Korongvale - Warrenheip bg) and (Maryborough - Maroona sg) will be unworkable unless Inglewood - Eaglehawk is re-opened for say 40 - 50kmh then the bg lines can run more than one train on each line per day. Spend
$ 20 - 25 m to re-open as fit for purpose (NO VLP "gold plating") and you more than double train capacity on the two bg lines, plus by cascade releases paths between Dunolly and Maryborough for more sg trains. Its a no brainer to not do so in the face of the forecast bumper grain harvest would be negligent in not making best use of the existing rail network assets,and would condemn daily up to 180 extra road grain tracks on local road networks.
Such project would use locally sourced materials and labour over 8 - 10 weeks in a job creation short term project for the region economy.