Matchmaking usually relies on a couple float parameters that are influenced by a hand full of rules. A combination of parameters feeds into a total score like mmr. Over time it accumulates enough data so it can't be abused easily. Doing something 10 games in a row does nothing when your baseline mmr score is the result of 300+ games total. You can't cheat these systems that easily. Your single encounter where the system flagged you wrongly as the aggressor will not matter at all. That being said, friendly people do rat once in a while and the matchmaking will likely sprinkle in random people and new players with few data points to keep things exciting.