Warner Losh has contributed to FreeBSD and open source project for years. He's used BSD only since 4.2BSD. During his long career, he's worked on a GUI builder/X11 toolkit; high precision time and frequency applications; pre-nvme PCIe flash drives; and high bandwidth video streaming. Most of his career has been using FreeBSD and that's allowed him to contribute to all areas of the tree. He's spent time in the core team leading the project. He co-wrote the bylaws of the project. He's also taken up the charge to get the packages project's bsd-user emulation upstreamed to qemu.