Experiences and advice vary greatly. I often wonder if some areas are getting E20 or something else....even though the pumps say 'E10". I can quote dozens....no, hundreds.... of examples of 'no problem at all' storing cars with E10.
In my neck o' the woods we've had E10 for umpteen years and I've never had any storage related issues that I didn't have with non-E10. Moisture/rust in fuel tanks has always been a potential problem, with or without E10. But E10 will absorb more water which is why you have to be extra careful
SO much depends on storage conditions. A wet environment can be a problem, yes....especially if the fuel system is unsealed. A dry environment, not so much...or not at all.
(In one extreme example, I recently un-buried two 2003 Corvettes that haven't been touched in over *five years* and they started up and ran on the E10 that was in the tanks! A little smokey, but they ran. Fresh fuel added....and now they're in regular use with no problems. Of course, they have well sealed fuel systems and were stored in climate controlled environment.)
Anyhow, I'd go ahead with some sort of fuel stabilizer designed for E10, yes. Can't hurt, might help, will assuage any worries....especially if the car will be in damp storage. But if the car is storage in a dry, temperature stable environment and for just a few months, I really wouldn't worry much at all, to be honest.
Cheers
DD