tl;dr version: three users including two admins revert-war a newbie past 3RR; one of them blocks the newbie for it, and doesn't block one of the admins, who had also broken 3RR, because the edits - made in good faith, and possibly even good edits - were supposedly vandalism. The blocking admin insists he did nothing wrong.
Introductory links: http://en.wikipedia.org/wiki/Special:Contributions/Mm555 http://en.wikipedia.org/w/index.php?title=U.S._Route_50&action=history http://en.wikipedia.org/wiki/User_talk:Mm555
Rschen7754 and TwinsMetsFan are admins; O is not one on en.
Mm555 appears to be a newbie, or a former IP editor, from the Carson City, Nevada area. Among his edits, he edited [[U.S. Route 50]] to add junctions with US 395 and US 95 to the infobox, and was reverted a few times, in my opinion properly, since having that many junctions for each state would make it too big. A comment was added to the infobox: http://en.wikipedia.org/w/index.php?title=U.S._Route_50&diff=prev&ol... stating that there were enough junctions.
A discussion on the talk page: http://en.wikipedia.org/wiki/Talk:U.S._Route_50#Junctions_list_for_US_50 basically agreed that US 93 is not a major junction and US 95 would be better; US 395 was brought up but not rejected.
Mm555, after reverting a change from US 93 to US 95: http://en.wikipedia.org/w/index.php?title=U.S._Route_50&diff=next&ol... decided that US 395 is better and changed to that: http://en.wikipedia.org/w/index.php?title=U.S._Route_50&diff=next&ol...
Personally, I think I agree; the US 395 and US 95 junctions are fairly close, and the US 395 junction is in Carson City, the state capital.
Rschen7754 reverted his edit "to good version", O made four reverts, and TwinsMetsFan made one. Mm555 ended up making five reverts. Rschen7754 warned him several times for vandalism, and O threw in a "Please do stop and read the guideline" ( Wikipedia:WikiProject U.S. Roads/Infoboxes and Navigation/Infobox , which it doesn't look like anyone linked him to); it's also about the number of junctions, not which one to choose. Nobody told him about the 3RR and nobody pointed him to the talk page discussion. TwinsMetsFan blocked him for 3RR, but did not block O.
I confronted TMF and O on IRC, and TMF said he didn't block O because O was reverting vandalism. They claimed that Mm555's edits were vandalism because he wasn't following the consensus on the talk page.
What should be done about this? The blocking admin insists he did nothing wrong; I didn't get a chance to talk with the other admin, who gave most of the warnings. Obviously Mm555 should be unblocked and apologized to, if he's not already gone. But how do we prevent this from happening again?