Look at their actions, not their words specifically.

It’s a culture where being unkind is particularly unacceptable, not specifically where you’re not allowed to be honest or forthright.

You’re allowed to not like someone, but telling someone you dislike them is needlessly unkind, so you just politely decline to interact with them.
You’d “hate to intrude”, or “be a bother”. If it’s pushed, you’ll “consider it and let them know”.

Negative things just have to be conveyed in the kindest way possible, not that they can’t be conveyed.