When I was running a Source server (TF2, but CS:S is Orange Box now too), I had problems with the 2.4.x linux_bases. I had to uninstall the linux_base port, then change the linuxulator kernel version:
# sysctl -w compat.linux.osrelease 2.6.18
Then reinstall a different linux_base for the 2.6 kernel. I might have the kernel revision I used wrong, I don't have that machine any more. TF2 and L4D ran without any crashes after doing that.
I think that guide's wrong/outdated too, I didn't have to compile a new kernel. Just mounting linprocfs was all I needed after installing the right linux_base.
My server ran great on a X3220/4GB RAM, FreeBSD 7.1.
Edit: That guide's definitely outdated, I'm 99% sure I didn't have to enter any credentials into the steam binary to get the dedicated server software.