Can PubNub filter chat message contents or user interface components for my app?

No, PubNub serves as a non-intrusive, high-speed messaging backbone for your app. PubNub does not inspect or alter the message payload in any way.

Filtering or altering message data is ordinarily carried out by the app, either on the client or server side. Similarly, PubNub does not dictate how message data is rendered on the client device. Implementing the user presentation layer is carried out by the app which has access to the message data via the PubNub API.