I think the stigma against having an Alt is because they are often used to either bypass a Trust Restriction (IE your main is red, so you make another to get around that) or to farm Signature Campaigns. Otherwise I don't see the purpose of having an alt in the first place
And I see one.
For example, if you're running a campaign, escrow, or any other forum business, you don't want people to know your personal opinions because that might impact your business.
If you, for instance, say you're supporting death penalty, or are against gay marriages, someone might not like it and avoid doing business with you. That's why it's wise to separate business accounts from your casual ones.
Whether someone having 2 accounts in 2 different campaigns deserves negative trust is another topic for discussion I guess. I'd still say no, because that person isn't breaking any campaign or forum rules and isn't acting dishonestly in any way.