I think the "match fixing is perfectly fine" crowd here is in the minority.
Along the same lines, I once watched a U10 boys match at a tournament. It was a tight match, tied, and parents were going crazy on the sidelines. One team scored, and that team's goalkeeper fielded a corner kick shortly after and then fell down and did a Neymar quad-roll grabbing his ankle. Play was stopped, the coach went out, the trainer went out. No attempt was made to stand or get up off the field. Parents were yelling "stay down", and I thought his ankle might be broken. He was down for 15 minutes, which was the majority of the half. Ref was forced to blow the final whistle, as the next game needed to kick off. Goalkeeper leapt to his feet and joined his teammates to celebrate the win, causing absolute mayhem on the sidelines. Security was called, accusations were made, and the team was disqualified. Was that against the rules of soccer? Probably not. Was it unethical and unsportsmanlike? Absolutely.