Yes, it almost certainly helps that Idgie has always taken on a generally masculine social role: she is clearly The Man in the relationship and therefore the whole thing fits easily into the regular pattern.

Jen Manion's Female Husbands (2021) would be relevant here if my copy weren't in storage. Highly recommended, though.

Watsonianly, it also strikes me as reasonable for the town to accept her family-building with Ruth because if the town had not been going to accept Idgie, she would have struck out on her own a long time ago.