I killed a player who was behind due to being AFK in the start of a game. Was i in the wrong?

I played ADC against an MF and Lux going bot, i quickly noticed the MF was missing. About 10 mins into the game MF came to bottom lane lvl 1 and tried to farm. I played lucian so i picked up an easy kill on her twice. Then i got flamed by the enemy team and one player from my team. Saying i was bad and how i had to kill AFK players. I told them i had no responsibility over MF being AFK and if anything they should be mad at her for being AFK. Was i in the wrong? It was a ranked game.
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