Strategy for demoting fast?

In two matches today there were two premade players where one of them leaves, and the other one makes it difficult to win. Then, exactly on match point the premade who left rejoins. Is this some kind of strategy to demote and smurf? Does this trick the punishment system in a way where it doesn't count as an abandoned match?

True for both matches:

• Player A & B have similar names, suggesting they are premade

• Player A leaves on round 1

• Player B stays behind, missing easy shots/playing dumb/pinging wrong positions

• Player B doesn't talk for the entire round, before it's down to me or my mates to clutch, at which point they won't stop talking and we have to mute them.

• Leaver rejoins on match point

By now I am just frustrated, and I guess I saw some sort of pattern and went full conspiracy theorist on the whole deal. I just started playing R6, so I'm wondering if this is a known thing, or if anyone else has experienced something similar.