People got mad at Zuke because she implied she wrote Peridot and Lapis as a married couple, think she also posted a couple sketches. Nothing actually concrete or anything. A large part of the fandom shipped Peridot with a different Gen due to an earlier episode, and when they heard Zuke put in hints toward a different pairing. they REEEEEEEed hard over it, attacking her in Twitter and accusing her of queerbaiting as well as attacking her of the Bismuth episode. All of this happened the same time as her birthday, so she left Twitter over it. I'd imagine she quit shortly after because she was sick of the fanbase.
When people say she "ruined" Peridot, they mean "made her close friends with Lapis instead of having her be lesbians with Amythest". So if Zuke wants to post stupid shit like that to make those fans REEEEEEEE more, I'm all for it.