The comment was not rude. It just wasn’t gushingly encouraging.
You’re VERY close to this, OP, and clearly emotionally invested. At a certain point you’ve got to buy the horse that speaks to you, but people here are also looking out for you by throwing in some reality checks. There’s a lot of yellow flags here in this whole deal.
Realize that you’re new to this, have some regrets related to a previous horse, and are maybe projecting those onto the older mare and this baby. Which is fine, as long as you realize that and make informed decisions around it.
Breeding and young horses are a big gamble, and there are some very knowledgeable and experienced people here giving you good advice. That doesn’t mean you have to take it all, but nothing here has been rude. Especially for the internet.