Just had that too and guess what though. Once again had a match with 2 non shield tanks and then a leaver right after the time limit where it would have cancelled the match. I am now at having 19 leavers on my teams since the last time I played a team that had a leaver after the beginning time limit.
The leaver likely left because on Hanamura with 0 shield tanks guess how fast the other team rushed in to cap the first point without a shield tank? Pretty quickly.