post s5 they should go ahead and release that blooper i KNOW they have of finn and noah dialing the romance up to 100 in the 'friends... best friends' scene just for the shits and giggles
But I want to know why Noah said that in the first place. The way I see it, there are three possibilities:
Noah was trying to improvise something but it didn't work (I really don't think this is it but it could theoretically be possible)
This line was in the script originally but then they cut it and Noah forgot and accidentally said it
This is a line from a future heart to heart between Will and Mike and Noah accidentally said it at the wrong time
Now, if we had the script for this scene, we'd be able to see if option 2 is correct or not. It makes sense for the line to be in the scene, something like, "He's been good to us and good to El but, he wasn't able to protect me, not when I was the spy. That was you guys who saved me. That was you guys." It fits, but it doesn't really fit with Noah's tone of voice in the scene compared to the blooper.
Option 3, however, is very compelling. Of course there's speculation that they have already filmed parts of Season 5, specifically pre-time jump parts, so it's possible that this is a line said by Will in season 5 during yet another heart to heart with Mike. They could be talking about Will's past experience with the Mind Flayer/ Vecna and comparing it to what and how he feels now.
I'm sure if option 3 was true, they honestly probably wouldn't have released that blooper, but considering how the Stranger Writers liked trolling us on Twitter...