I've never seen an airfield there but there is
common land on the West side of the island that you could land a rotary on (nice and flat, smooth grass) but you would need serious STOL perf on FW. If from Glenforsa then both David H (airfield) and Alison W (hotel) do car hire which gets you to the ferry point for Iona, then CalMac for the 10 minute crossing.
h-r