Ah yes, the "extended Berkeley Packet Filter".
Wikipedia:

eBPF is a technology that can run programs in a privileged context such as the operating system kernel.

Phoronix:

Hornet uses a similar signature verification scheme similar to that of kernel modules. A pkcs#7 signature is appended to the end of an executable file. During an invocation of bpf_prog_load, the signature is fetched from the current task's executable file. That signature is used to verify the integrity of the bpf instructions and maps which where passed into the kernel. Additionally, Hornet implicitly trusts any programs which where loaded from inside kernel rather than userspace, which allows BPF_PRELOAD programs along with outputs for BPF_SYSCALL programs to run.

So this is to make kernel-level instructions from userspace (something that's already happening) more secure.

The thread linked by the OP is Jarkko Sakkinen (kernel maintainer) seemingly saying "show your work, your patch is full of nonsense" in a patch submitted for review to the Linux kernel.
Edit: the OP has edited the link, it used to point to this comment in the mailing list chain.