The reason champions like Riven/Katarina are almost never seen as support picks is because of how dependent on items she is to be playable in the mid and late game, which means that if she doesn't get a bunch of kills in lane, she'll fall off super hard. So the key in any matchup where you're against some unconventional support pick is to play extremely carefully and even if you fall behind in farm, absolutely make sure to deny kills to the enemy support, and ping if they could be roaming mid or to your jungle. Being behind 20 or 30 CS at 20 minutes won't matter at all compared to the enemy team essentially being a 4v5.
When it's two melee champs bottom, it's what is called a 'kill lane', because their sole goal is to try to get as many kills as possible and snowball. Classic examples of this are Blitzcrank/Alistar or Leona/Jarvan, but they're very rarely played because it's extremely difficult to be successful against most standard ADC/support matchups. As a brief history lesson, 'kill lanes' were the meta near the start of this game, with ADCs usually being sent mid, but this meta was actually defeated by the current setup of support/ADCs bot. So they're trying something that used to be strong but specifically was wrecked by the current meta.
With an Alistar support, the lane should actually have been very easy if he played correctly, since you can poke Riven/Katarina with volley and Ashe's superior range, and if Alistar stays close to you he can prevent any all-in attempt by Riven or Katarina with headbutt and pulverize. In order to lose the lane, either he probably used his abilities at very improper times to give her a window to engage, took too much harass from Katarina Q's, or just walked too close to Riven.
