My theory on this partnership: This and the Portland Ikea are the only Ikeas in the entire PNW. The next closest Ikeas are San Francisco and Salt Lake City! It's very possible that people are making extremely long journeys to go to Ikea and furnish a new house, dorm, whatever. I know growing up we would take about a two-hour drive to Ikea every few years for kid's room stuff.
If there are superchargers onsite, it's now a super easy round trip, even if you're 200+ miles away.
Also worth noting that there are already L2 chargers at this site. So anyone that just wants some opportunistic charge without idle fees can do that today