I think a five-year-old with an infant sibling might be difficult no matter how he was parented as an infant himself. You have to respond to children in their current stage. That's why I'm vehemently opposed to parenting philosophies that are based on the idea that you deny comfort to a baby in order to turn him or her into an independent adult.
This is a modern tragedy to me, and always will be. Why would I want an independent 5YO ? Why is that prioritized? To this day when people spout the blah-de-blah about 'socialization' and school, I look them straight in the eye, smile, and say "That's what I'm trying to avoid."
When I call myself ridiculous, I mean it affectionately! I am good with being 'ridiculous..' Up with ridiculous! I take my kids into the bathroom ( ridiculous??) I am not eager to leave them ( ridiculous??) and the big one, I don't put my babby down much ( been told many a time I am 'ridiculous.." ) Not going to change. I think most mamas here are proud of those differences, though the 'ideal' model may differ. Ideal being hopelessly subjective anyway.
Still, I can't say no, until I am worn to a shadow... Probably not a challenge in the 'ol animal kingdom.
Cherishing the different viewpoints, all from the heart.