There are a lot of myths and legends around cast iron that are due to older circumstances that are no longer applicable. And spray on oil seems like a pretty efficient way to season given that it’ll apply a fairly light and even.

A good seasoning should withstand some pretty brutal punishment. And even if it doesn't, you can easily reseason the pan which you'll have to do from time to time regardless.

I season my cookie sheets the same way. I've put them in the dishwasher, hit them with those steel wire soapy things, used barkeeper's friend, not much has taken the seasoning off once it's on there.

Except for lemon juice. Lemon juice fucks it right up.

I thought the concern was rust more than anything

I don't put mine in the dishwasher and I don't use soap when cleaning mine (cleans easy enough with hot water, dish rag, and sometimes steel wool), but I don't season either. I just use a refillable oil spray bottle.