that post has me thinking about the stoplight system as a whole. I think when I first started using it "red" was like. lets end the scene, lets stop playing, i need aftercare. And i think this works okay. But it feels to me like a misuse of the system that results in a lot less freedom to play.
The way I use it is as follows:
Green-> I can take more, i'm having a good time, keep doing what you're doing.
Yellow-> If you keep doing that, i'm going to have to call red soon. I'm getting near my limit but I CAN take more.
Red-> stop what you're doing and check in.
This allows for like, in a heavy impact scene i'll be hitting my boy and then he'll call yellow and I make a mental note. That's information. If I keep hitting him in that way, or in that place, or that hard, he's going to need to stop soon. Sometimes i DO stop and check in and see what's going on. Other times I keep going just to see how much he can take, then he calls red, and we take a breather.
I've never met anyone who offers up a Green without being checked in with. "Hey, can i get a color?" "green" "okay cool" and then I know that alls good.
Red works best as "stop and ask!" not as "stop and start aftercare, we're done." This way, if i'm doing something he can tolerate and he goes "red!" i go "whats up?" and he goes "Oh i just don't enjoy that" and I go "okay cool" and we continue the scene but now i have more information on how to help him enjoy it. Other times he goes "red" and i go "Whats up" and he goes "I'm feeling bad i wanna stop" and thats okay too. The key thing is I don't assume red is a hard stop.
When someone calls red I:
stop what i'm doing immediately
Check in, ask why they called red, what they need
Along side this, its so key to remember that you can have more than one safeword. In every day play my partner and I use the stoplight system as detailed here. But we also have a separate safeword that means "if you keep doing that, i'm going to need to go to the hospital." This lets you set up specific safe words. If you're someone who DOES sometimes need a safe word that means "stop everything and give me aftercare" you can pick a word to mean that.
All of this is to say, you can use the stoplight system as information and then you can also set specific safewords to mean specific things. The key to responsible kink will always be clear communication, and sometimes that means communication about your communication.