
There's a lot of discourse on Andrew recently so I wanted to add my 2 cents.
Based on my reading, Andrew's current 'possessiveness' is really not that bad. Rather than being excessive, unreasonable, or overbearing(which we see often in webtoons lately), it seems like Andrew is just extremely enthusiastic that he finally has someone he loves and trusts in his corner. As a result of his enthusiasm for Luke AND his lack of prior proper/positIve social experiences, Andrew is essentially a little socially stunted and is struggling to understand the boundaries and navigation of his relationship with Luke.
I'd argue that once he develops better social connections with others and feels more settled in his relationship with Luke, the 'overbearingness' would dim down. His clinginess now is just him not knowing how to handle the enthusiasm for this new dynamic with Luke.
The whole thing with the scissors and malcom, my guess is that the author put that in to highlight Andrew's awkwardness and how easy that can be misunderstood. Essentially, others like Malcom see his almost stand off-ish and clingy behavior and easily misinterpret it. Thus, Malcolm's initial reaction is something negative about the scissor incident. But rly, it's just Andrew being awkward/love-drunk, and easily misunderstood. This is in stark contrast with Luke, whose sociability makes him beloved and trusted by others.