Sharing your key with someone in the same house isn't an issue. Did you already forget about my post last night?
Key sharing among multiple people spread over multiple ips is a disaster waiting to happen. Browse through some old dramas like I said and you'll see MANY instances where key sharing has led to trolling, impersonation, arguments over the key, etc, etc. I mean it's really not hard to figure out.

Heres a good quote from the other topic
Why share your key in the first place? It's dumb.
Your key is insecure with anyone else but yourself. Can you ultimately trust whoever you give it to for them to not disclose it or not have it revoked? People could also use your identity. Doing things they should not be doing.
What if you want to come back to Blockland?
What if the person you shared your key to does something that taints your reputation?
There's many things that could go wrong. But there is nothing that could go right if you give your key out.