This link is actually very useful.
It is used when you click on an IP address in the log entry. The IP will be sent as search query to https://duckduckgo.com . The query contains a so-called Bang “!whois”, which is DuckDuckGo’s shortcut to forward it to its preferred IP resolving service (currently https://whois.domaintools.com).
In case you never heard of DuckDuckGo: It’s a very good search engine, mainly focussed on user privacy. It is —in my opinion— 100% trustworthy.
You may say, whois.domaintools.com should be hardcoded in the plugin so that the IP gets transferred straight to them. But the detour via duckduckgo.com also makes sense: if one day domaintools.com stops to work (or starts to suck), the people at DuckDuckGo presumably will redefine the “!whois” bang to another IP service. This way the plugin can continue to work without any code change.
@solarissmoke: I vote against the removal of the link!