So was the Remain option, using your logic.
What's isolationist about leaving an inward-looking, highly-protectionist union and becoming more outward-looking and global?
There's nothing isolationist about Brexit. Britain is a member of many other multinational organisations: ADB (nonregional member), AfDB (nonregional member), Arctic Council (observer), Australia Group, BIS, C, CBSS (observer), CD, CDB, CE, CERN, EAPC, EBRD, ECB, EIB, EITI (implementing country), ESA, FAO, FATF, G-5, G-7, G-8, G-10, G-20, IADB, IAEA, IBRD, ICAO, ICC (national committees), ICCt, ICRM, IDA, IEA, IFAD, IFC, IFRCS, IGAD (partners), IHO, ILO, IMF, IMO, IMSO, Interpol, IOC, IOM, IPU, ISO, ITSO, ITU, ITUC (NGOs), MIGA, MINUSMA, MONUSCO, NATO, NEA, NSG, OAS (observer), OECD, OPCW, OSCE, Pacific Alliance (observer), Paris Club, PCA, PIF (partner), SELEC (observer), SICA (observer), UN, UNCTAD, UNESCO, UNFICYP, UNHCR, UNMISS, UNRWA, UNSC (permanent), UPU, WCO, WHO, WIPO, WMO, WTO, ZC.
Again, you're going down the Remainer route of thinking of Brexit in terms of money and economics and what it means for such things. Most of the 17,410,742 people who voted Leave did so purely to regain the country's sovereignty and independence, and were willing to do so even if the economy took a short-term hit.
Only for Remainers is it about economics. For Leavers, it's about sovereignty.
I wouldn't reword it. I don't agree with undemocratically gerrymandering the Leave option.
There's no comparison between NAFTA and the EU. NAFTA isn't a burgeoning nation state like the EU.
Canada hasn't given up the dollar to adopt a new NAFTA-wide currency. 90% of Canada's laws aren't created by unelected Americans and Mexicans at the NAFTA parliament in Mexico City. Canada doesn't have to accept unlimited numbers of migrants from the rest of NAFTA.
If Canada was part of an organisation that is identical to the EU, you'd be wanting out.