The entire tortle question is a wide spread for me. It reminds me of a friend who works in theater and discussion about work led to talking about both prima donnas and divas, so I had to ask "what is the difference". His answer was that "divas are worth all the extra effort they demand." I have a very allowing homebrew, I just built it to accommodate things like 'circus troupe parties". Stiil, theres a wide difference between in the PHB, in a book I own, another book that is for 5E, some book from three editions ago, or just because. If a regular player of mine wanted to play some weird tortle character, sure. If a new player posited the idea during character creation with everybody else and they didn't have any issues, sure, I'd make it work. You get to a player coming in the middle of campaign and waiting choices the others didn't have that may go against the flavor of the game, I'd have to really wonder if they were worth the extra effort. If another player I trusted and who knew them started talking about making a ranger that hunted tortles, I'd probably be worried when I pulled them over to ask what was up and already thinking of ways I could say "sorry, we're full".
As for lynch mobs and massacres of villages, I'm probably not worried about them burning down my setting. It's mean to be a sand box. Still, by that time, they would have gotten several warnings including an OOC "Are you sure? This is an action that your charatcer would know will have drastic consequences." For simulation sake, I've always been up that polities are very concerned about up and coming heroes. Things like annoying taxes and other bits are there just to highlight lower level adventurers so those that aren't willing to play the game can be prunned before they become a real problem. Triple so for a setting where the commoner is just a 0-level and population doesn't work off the same rules as the PC. The idea being that such people who toe the line will be allowed to buy into the system. Like I said, in a game where the campaign was about overthrowing the Lich King, the party would have known all that before they massacred all those gnoll men, women and children.
ETA: I will also say that I have been trying to catch up with this thread for the past four days and finally did so since I took the day off work today.