It’s worth making whatever kind of submission you can manage for this. The page even specifically notes: “Due to the short timeframe of this inquiry, the committee would appreciate submissions being limited to 1-2 pages.”
This bill will affect all users of social media in Australia, and may have a particularly negative effect on Fediverse platforms (like Lemmy and Mastodon) which are operated by individuals or small organisations that may not have the resources to implement age verification.
Personally, I agree with the sentiment, my concerns are mostly with implementation. If it actually is based off a blind signature like I’ve heard some people suggest, I’d be pretty okay with it, but otherwise, I’m not a fan.