Your colon does not really solve ambiguity. They likely thought you meant "I love C: performance and security." which would make it more explicit, but it would also change the meaning and thus be incorrect.

If I thought it was ambiguous enough to really try to fix, what I would probably default to is an elaboration. For example: "I love the intersection of C, performance and security." The meaning is not exactly the same, but it is more the same than your colon.

I suppose my reading was essentially as "These are a few of my favorite things", i.e. that I love each of them, and it would be quite nice if I could enjoy all of them at the same time, but it's not that I only love their intersection.