I think it would be fine if the message came up as something similar to deleted messages, so like:

Username: This message is blocked

Or something along those lines. This would keep the uncomfortable message away from you, while still allowing you to know that another user in chat exists.

Although I get where the idea is coming from, the first thing I think of is just the increased amount of work the prefect teams would have with this feature, and I kind of get a headache just thinking about it as a prefect leader myself. The idea itself isn't bad, but the system would quickly get abused and go out of control with troublesome comments, harsh criticism resulting in fights and so on. Many users, including myself, wouldn't be comfortable with others commenting on every little thing in the topic. Moreover, imagine a new user taking part in their first topic, and immediately get shot down by harsh criticism or unfriendly comments about their character and/or writing. Comments that people wouldn't go out of their way to owl someone would become more common as it becomes easier to send.