The more I think about it
the more I'm convinced the "Grand Final" is key in this case.
Your theory seems plausible.
High emotions & a few??? drinks & driving & Gus merrily marching enjoying his unexpected adventure.
Plus the dusk setting in.
JMO
To add to my post...
I forgot to mention
that this outstanding sports event (Grand Final)
broke the usual dull ROUTINE in daily living.
And when known routine is broken
unexpected & unforeseen things might happen.
Sudden disruptions.
Sometimes chaos & disorientation.
JMO