First, your campaign is your rules. If you don't want to allow newbie to participate in your campaign at any section because probably most of them are alts
[as you described in the OP], then you have the right to apply that rule to your campaign.
Second, I have asked or suggested the same question in the past about limiting the participation of newbie in the campaign, but look at the reaction community.
Should every newbie have a limit in the bounty of social media?Then I'll have to think twice about this post even though I've suggested the same a few times about newbie when some cheaters hunter catches big farms.
Limiting newbie participation is very harmful for a community. Newbie jail will never return: I consider the newbie-jail period to have been extremely damaging to the forum. When barriers to participation are too high, then the best people often just won't go to the trouble of joining, and the people who are willing to jump through the hoops are often people who aren't good for the community: people with nothing better to do, scammers, get-rick-quickers, etc. Having a permanent newbie jail policy would improve things a lot in the short-term, but would end up being a fatal poison to the community.
I don't mind a newbie participating in conversations on the forum, which is what I believe theymos is referring to in your quoted post. I have an issue with a Newbies participating in bounties making money. 2 totally different things IMO.
I welcome Newbies to post and interact on the forum. We were all Newbies at some point.