Griefing, but not inting

I just played a game where a Blitzcrank threw down control wards in mid lane level 1 to gaurantee my opponent an early level 2 and some gold. I said to my team that my lane was going to be harder now, but I refrained from flaming the Blitz. He proceeded to do it again level 4, giving about 120 gold to my laner, and some XP. He proceeded to roam for ages, being down a level or two compared to the enemy support, and played half-heartedly the rest of the game. We managed to sweep the enemy team and secure a victory, but it had me thinking. What does Riot do about this? I've been seeing griefers do small things to ruin a game here or there, but they don't int, meaning Riot's bots likely don't detect it. I haven't seen anything about submitting video evidence as well, which makes me a tad worried. Apart from sheer luck of the player already having a large amount of reports, is there anything stopping people from doing these small griefs that certainly impact a game, but don't entirely throw it?