I afk'd first frame because my parents called and the dude did a decap opener, I managed to block it and the game went on just fine, later in the match I got the decap myself and everyones claiming its rigged, even though you can see I struggled to get it for a while, what do you guys think?

definitely not rigged bro.
You can tell by his movements to get ur hand off of his head.

Your opponent could have easily decapped you too, if he just let go of your neck your head woulda went * Pop *. I'm just guessing that he's more competitive, which is the reason why he got mad and said it was "Rigged".
Gg.