No.
Exposure to a small universe of listed equities does not prevent responsible investment.
Negative screening and exclusion are only a sub-set of the available tools for responsible investment where divestment is a related and powerful tool to send a strong signal about a particular company or sector.
However, there are a variety of other tools you can use. Stewardship or active ownership is one of the most powerful tools. It means actively communicating and engaging with companies about your expectations on key ESG issues and collaborating with other investors to influence change.
Importantly, the Acting in Concert regulations do not prevent collaborative engagement on responsible investment strategies.