I wanted to jump in here, because there has been a significant amount of controversy regarding this vote.
To summarize, by the time the voting period concluded, 12 voters had not cast their vote. More than 60% of those who did cast votes voted to ban Mega Metagross. However, when taken as a percentage of all qualified voters, Mega Metagross did not meet the proper ban threshold.
Funbot28 was correct in basing this vote as a percentage of total eligible voters. Our tiering policy is intentionally set up so that things that change the status quo only happen under exceptional circumstances: a majority of the community feels that there is significant need to address an issue within the tier, meet the voting requirements via a suspect test and then casts their votes to make a change. "No change" should always be considered the default position in any test, because non-usage based tiering changes are meant to be exceptional events that only occur when necessary for the health of the tier.
Yes, this does mean that not voting is essentially the same as voting to preserve the status quo (either do not ban or keep Ubers/BL, depending on whether this is a vote to ban or unban something). That's because the alternative is worse: in an extreme example, you could end up with cases where so many people don't vote that only a handful of people, or even a single person, end up banning something. That's a situation that I think needs to be avoided. If 100 people went through the process of laddering/getting reqs/identifying as voters, then there should always be a barrier of 60 votes required to ban something (or 51 in the case of lower tiers), regardless of how many people actually cast their votes.
So, from reviewing this, the OP should stand: as Mega Metagross did not meet the minimum threshold for a ban, it should remain legal in NatDex OU.
I believe that a lot of this confusion was due to two factors. First, the OP did not state the minimum ban threshold or clarify how many votes were needed to constitute a ban. Many tier leaders (myself included) do include this information in the OP of any voting thread, and I think doing so would have made this far more clear. However, this is no fault of the NatDex leaders but rather a fault of my own, as I have not established a standard OP for suspect voting threads. I plan to change this shortly, and create a publicly viewable thread including resources such as sample OPs and clarifications regarding the voting process, so that information like this is always explicit.
Second, the vote was left open for additional voters after the deadline, despite the fact that doing so could potentially sway the vote. Sometimes tier leaders do leave votes open after they conclude so that people who qualify to vote but who didn't get a chance to vote can still place one for purposes of qualifying for the TC badge. However, this obviously should never happen in a situation where post-deadline votes could potentially change a vote's outcome. (I'm also personally of the opinion that threads should be locked at the deadline regardless, because if you haven't managed to vote by the deadline, then you haven't really contributed anything to tiering, but that's another discussion.) Again, this is something that wasn't previously publicly stated, so I'll make sure it happens in the future.
This discussion also raised some legitimate concerns about voting Abstain, which I believe aren't super relevant here but deserve a more full discussion; I'll create a PR discussion on that shortly.
Watch the Policy Review forum for more general discussion about how we should handle things moving forward, and expect a stickied thread on voting procedures to be added to this forum sometimes this week. However, this vote will stand as-is, and Mega Metagross will remain legal. Since there is a clear case of community divide on this issue, if the tier leaders choose, they can re-suspect Mega Metagross down the road.