The signature campaign did nothing but clog up the thread with drivel and bring a bunch of freeroll leeches to the site. They would be better off paying some live pros to wear swc merch at tourneys.
Signature campaigns are usually effective for a long term brand buildingrather than immediate results.
You may not like it, but that's essentially what freerolls are for. To attract new sign-ups and allow them to test the site risk-free, with no deposit needed. Some portion of them will never deposit any own funds, but there's always a chance that a few of them will convert into real and loyal players. Some of them could be young people without any real income, but they might return later to play bigger stakes.
I'm not sure if advertising via live players wearing merch would be any more effective. Only the top players get a decent media exposure and they are not cheap. Plus, they probably wouldn't be very keen to advertise a niche site they don't know or trust.
I think advertising via online poker-related content creators (i.e. site reviews etc) could work much better.