So, it has been about a year or more since I read 13 give his own story on what happened and why he decided to permanently stop development completely. He gave a detailed account to those of us at a specific subscriber tier (I can't remember how high). The following is going to be much shorter and more vague between an attempt on me to respect his wishes for things to stay as private as possible, and me just not remembering due to also having left the discord server since.
Many people, due to the way that 13 wrote his final public messages, immediately blamed his wife, but he made it clear that this was absolutely not the case. His game development had become something of an obsession that ate into his free time and strained their marriage, but he and his wife had found ways to make it work by using the extra money he was earning to go on vacations together. Many fans speculated that the loli and incest subject matter were what made his wife tell him to stop. Again, this was not the case. She was aware of the subject matter, and while she was decidedly not into it, she told him that it was his thing and she didn't mind so long as it was kept away from her eyes.
The true reason why 13 decided to end all game development was due to what sounded like a fairly traumatizing incident with law enforcement. I'm certain 13 mentioned being from the US, but I don't remember if he said which state he lived in, and I wouldn't tell if I did know, so the legality of loli depending on what state he lived in at the time is in question. On their return from a vacation overseas, 13 and his wife were pulled aside by customs agents and separated. At first, they thought it was a routine random inspection. It was not.
First his wife was grilled. Then he was pulled in and questioned. I can't remember if he said if this was just border customs or the FBI, but the agents had him unlock his phone and show them his discord server for the game. They asked him where on the server they could find the real CSAM. 13, taken aback, explained that there was no real CSAM on the server, only fictional pornographic content of teenaged characters. He happily showed them everything, but they routinely tried to catch him up by asking the question over and over again in different forms, a typical interrogation tactic. After a lengthy amount of time, they told him he was free to leave, but his phone, devices, and hard drives all needed to be combed through for illegal material. 13 told us that they found nothing because he had nothing of the sort on any device, and since he was able to update us months later, clearly he was telling the truth. I can't remember if he said if he ever got all of his devices back, though.
Keep in mind, Westy's arrest by the Australian government was still fresh in everyone's minds around this time, so 13 decided that one incident like this was more than enough. I can't remember if he said whether or not his wife had a hand in this, but given his account, I fully believe that he would've come to this conclusion no matter what. He simply did not want to risk his freedom for what he considered a fun hobby that pulled in some extra cash. He told us that he deleted everything that had to do with any games he had developed and would cease completely with absolutely no intentions of returning. Even if they hadn't arrested him now, who could tell when loli content would be made fully illegal or not. The risk simply wasn't worth it.
My theory? Given how many loli devs have been targeted over the years, I have no doubt that some overzealous loli hater, enraged by pixels, reported 13 to the FBI or similar authorities, and they managed to find his real identity. Since they couldn't get a warrant to search him for loli content alone and with nothing to suggest probable cause for a search warrant, his information was sent to US Customs and Border Protection to flag him down and search him the next time he reentered the country. It's a sneaky trick to avoid going through the difficulty of getting an actual search warrant.
In any case, 13 almost certainly doesn't plan on coming back unless the legality of loli content is enshrined into law or something. It's a shame, as dozens of loli devs have fallen victim to moral keyboard crusaders over the past few years.