This is outright false[0] - 27% of Ontario's power is gas, with a possibility of 59% nuclear[1] but the nuclear infrastructure in Ontario is aging and shutdowns/refurbishments is pushing Ontario towards >50% gas (and imported coal/gas) as of this summer[2]. Further, per IESO[3] Ontario is facing a 2GW shortfall this August. Maybe if not mismanaged, Ontario could be an exporter - but the joke is that's not the case anymore
[0]https://www.ieso.ca/en/Learn/Ontario-Electricity-Grid/Supply... [1]https://www.ieso.ca/en/Corporate-IESO/Media/News-Releases/20... [2] https://app.electricitymaps.com/zone/CA-ON [3] (PDF) https://www.ieso.ca/-/media/Files/IESO/Document-Library/plan...