They said explicitly they do not have any issues with an offline modded client of Skate, but the problem is that Reskate did not do anything to stop people unlocking paid content and releasing content before it's meant to be released. Those are completely reasonable requests.
A lot of Reskate mods are just enabling things that are off, because they are either unfinished or waiting to package them in an update. The Hall of Meat mod is exactly this; "It draws only skate.’s own assets from your install." You might say "Why are they holding things back from us, it's early access" Game developers don't just make features and stuff, they have to specifically cultivate an experience, an atmosphere, a mood. If they just dump a new feature in a random patch without any onboarding content (Hall of Meat with no challenges to do would be like having a pool floatie without a pool) it would suck.
Also, a majority of the content of mods is stolen from other games or resources, modders don't have to license anything. A bunch of copyrighted work is taken with zero royalties and zero compensation to the artists - not fair at all.
Let's take the San Van at night map for example, if you look at clips of that, the lighting is completely off and the streetlights only light a very small pocket of the road, rather than ambient lighting making it look realistic. The weather is another such case, these features are experimental and not finished. Adding unfinished, experimental things to a game rather than building it strong and stable with each week creates all sorts of headaches down the road.
So to summarise, nobody has an issue with Reskate at face value. The problem is comparing Reskate and Skate, when they are working with completely different limitations in mind. Nobody who worked on Reskate has an issue with Skate. It's just people who seemingly have an issue with the game because it's different.