In no universe is Wilder scared of a fat plodder like Ruiz, particularly after how Ruiz has looked since the lucky punch. Ruiz is living in a fantasy where every HW is scared of him when in fact I doubt any ranked fighter ISN'T happy to fight him. That's okay though. Ruiz will only get fatter and slower as he ages and soon he'll start getting KO'd.
Pretty clear that neither windmill nor rice pudding jnr want to fight unless they are ridiculously overpaid. They're both basically semi retired.
Ruiz likely did a lot to not make those big fights happen. That being said: anybody thinking Wilder or his team are not afraid of Ruiz is still buying the narrative they've been sold years ago (Wilder being a legit champion.) The man fought nobody top, except for Fury who badly shortened his life expectancy twice, and Ortiz who even though tailor made (bad gas tank, bad chin, old) mad the A-side outright cheat after being rocked. It's a risky fight for both.
Wilder and Joshua were trying to Tank Davis Tippytoe their way through boxing but they ended up getting embarrassed by underdogs. No one should expect either of them to be running into the fire. Old man Ortiz, a then 42 year old, is Wilder's biggest risk besides Fury. Cashout phase now. Stop listening to promoters and soundbytes.