It's one thing for you to put a banner up on your web page, which I will see when I visit you. I can just choose not to visit, if I don't want to see your message. It's another thing for you to put a banner inside my computer , on the software I use to manage my own data : that ought to be a tool I use for my own purposes, and not a place for you to do what you want. A tool which starts acting as an agent for its dev…
If you trust the makers of LibreOffice enough to run their software on your machine, you might also want trust them on this decision. Unless of course you know better than them about what it needs to keep the software alive you run regularly.