This may be a long trip between Six Nations and Hamilton / Aldershot, but remember that this is in consultation with Six Nations. It may be possible that going to Brantford is a higher priority; it is the home of their other reserve lands (Glebe Farm) and the Woodland Cultural Centre (former Indian Residential School turned art gallery, museum and library, and possibly home to undiscovered grave sites). There may be other important economic, social and cultural places for Haudenosaunee people that are more important than the GTA.
In fact, I'm shocked that Toronto-centred GO Transit is not running the shortest route. That said, if there is a desire to do that, service via Caledonia and Hamilton Airport would be a great side benefit for others.