score:5
Travel is certainly possible. Punta Arenas has 120,000 inhabitants and Ushuaia on the Argentinian side has 60000 inhabitants (with ski resorts apparently opening in June). Advisable depends of course on what you want to do.
Wikipedia has useful information on climate:
Puerto Montt, at 41°28'S, has 6.0–12.7°C in May:
Much further south, Punta Arenas (53°10' S) has 1.0–6.4°C in May:
Cold is relative, but if you take appropriate clothing you should have no problems travelling in May.
Disclaimer: I have never been to Patagonia, all information is from the world wide web.