Looking at the past activity on meta, it seems that quid had silver discussion tag-badge before they deleted their account. (However, not a gold one.) data.stackexchange.com/meta.mathoverflow/revision/1052339/… data.stackexchange.com/meta.mathoverflow/revision/1052337/…

Todd Trimble seems to be quite close to the second one: meta.mathoverflow.net/tags/discussion/topusers (And I guess that some time will pass before the first gold tag badge on MathOverflow Meta.)