yeah it's a tricky question, I mean Red Teams can never fully emulate all classes of attacker as they're still constrained by laws, but more realistic red teams provide more realistic tests :)
What seems to be the case is that lower end attackers who don't have the skills to create fully custom setups (or high end attackers who don't want to risk their own tooling getting discovered) will use "pentesting" or red team tools to enable their attacks.
So the line (if there is one) is how much do you release in that direction. Some/Many people draw the line at dropping 0-Day others might draw it lower or higher...
"Dropping 0-day" usually refers to the act of releasing an exploit for a previously unknown security vulnerability, prior to the product owner being able to deliver a patch for it.
What seems to be the case is that lower end attackers who don't have the skills to create fully custom setups (or high end attackers who don't want to risk their own tooling getting discovered) will use "pentesting" or red team tools to enable their attacks.
So the line (if there is one) is how much do you release in that direction. Some/Many people draw the line at dropping 0-Day others might draw it lower or higher...