Bulma and Table met during Tarble’s one on-screen appearance, so the actual answer here was kinda obvious. I thought it’d be fun to explore their dynamic a bit, since we don’t see them interact much (or maybe at all, I can’t remember) in “Yo! Son Goku and His Friends Return!!”. Given how I’ve characterized Bulma up to now, though, it should be no surprise that there’s a lewd element to their relationship.
This commission wanted to show Vegeta with two somewhat similar characters in his life, his little brother Tarble and his somewhat protégé, Cabba. Both are short, skinny Saiya-jins with kinda similar designs, though Cabba seems to be a much more competent fighter than Tarble (who’s basically a pacisift, as I recall). The commissioner wanted to see what’s basically the moments right before a spitroast, with Cabba gripping Table’s cock while Vegeta’s pokes at his back door.