I hope that this doesn't evolve to a different problem. Lin is hesitant to voluntarily involve outsiders and invite them to meddle in our affairs. He doubts that if the intention is some kind of unsupportive, even without real ill will behind it, it could be fought out on his back. As the 'new' person in our relationship he thinks that he is likely the one who will get some negative feedback and be suspected of manipulating our relationship by the circle of our friends here.
But I doubt that there will be someone so troublesome around them. At least I hope so. Some just need to get themselves involved in the business of others. Especially if it's something they believe to be (morally) wrong. We will see how it goes. I personally don't mind that much, but I know how hard this would be on Sward, so I better not have the situation at all if possible.
And I think you are right, I would react positive if a friend told me like you phrased it in such a situation. A bad reaction is normally out of concern and I hope that our friends are honestly concerned about our happiness
Facts: 30, female, bi, v-type relationship with Sward (husband, straight, mono) and Lin (boyfriend, straight, mono), poly-fi and co-primary.