The only problem with this theory is that Greg already has number one and two google status, with the wiki page coming in at number three. Anyone searching for wackys is already going to Greg's site first, why worry about wiki? I suspect his motivation in changing the page had nothing directly to do with traffic or money.
Also, I don't believe he ever originally added his site to the page, rather someone else did. I tried going through all of the modifications, but it would take all day to figure out what really happened long term with the external links. When his link was removed and replaced, I'm sure that did bug him, whether his link is technically in violation of wiki rules or not.
EDIT: I just looked up the early history of the wiki site, and indeed Greg's site was first added as an external link on July 6, 2005 by someone at Brandeis University in Massachusetts.
I also looked up and searched the entire edit history. Here you go: Greg's site was removed for the 1st time as a Wiki violation (along with numerous other links) on July 29, 2007. It was put back up by someone other than Greg on Dec 14, 2007. It was joined by Ernie's link on July 17, 2009 and they were together until Greg removed Ernie's link on Sept 13, 2009. So Greg clearly started this "war" with Ernie. Ernie put his site back up on Nov. 25, 2009 and Greg removed it on Nov. 30, 2009. Ernie put it back up on Dec 2, 2009 and then an administrator removed both their sites the next day, Dec, 3, 2009. Ernie then put his site back up the following day Dec 4, 2009. Greg did not. This forum was then added for the first time on March 12, 2010. Ernie's site was removed as spam on Sept 22, 2010 (not by Greg). Ernie added his site back on Nov. 7, 2010. It was removed along with this forum the same day by someone with the name Tbhotch as spam (no idea who that is). Ernie added it back along with this forum on Nov 14, 2010. On Dec. 20, 2010 Greg kept Ernie's link name along with the forum's link name but replaced the URL with his own to direct them to his site. This is where the on again off again started which has already been documented here.
As for Old School, the first Old School paragraph was put up by John (Duzn't) on June 16, 2009 and completely removed by Greg on the same day he began removing Ernie's links, Sept 13, 2009. Some one then put up a new paragraph on July 21, 2010. I fleshed it out with the new info on OLDS2 on Nov 28th, 2010 and Greg removed all of it on Dec. 20 2010 and began the back and forth with this as well. Again all documented here.
The first removals which had Greg's very own name listed along with subsequent IPs (which all lead to Greg's neighborhood and his place of work) show Greg to be the sole person doing the vandalism.
I agree with you that Greg's motivation is not DIRECTLY related with money (but it certainly is indirectly related as far as Old School). He's just being a spiteful ass who is attempting to hijack the Wiki page and the hobby in general. Looking only to have his point of view and forum available. Not exactly a defensible position. You seem to be advocating a partial weak defense for him by mentioning that Greg may have been "bugged" by his site being removed but that was in 2007 and not by Ernie or anyone else doing so for spite. It was by a spam remover. Ernie and others had their links removed as well. The evidence clearly shows only Greg to be the petty child and aggressor here.