I take your google point, but what I was thinking of was that name changes are tracked, and in the ticket, original username is shown, and a link containing UID is given. That means, AFAICS, that UID is ideal but one of the user's past names would also do.

(still, tickets are not searchable, so that would entail spidering through ~18000 tickets , given that original username is NOT shown in the index. Definitely an improvement.)