Cannot upload key without UserIDs but with valid Direct Key Signature

Hi,

I'd like to upload a key that doesn't have any User IDs but only a Direct Key Signature, such as this one:

-----BEGIN PGP PUBLIC KEY BLOCK-----
Comment: 7D02 7E4E 7CC6 8DA9 7ABC  474C AF16 AAB8 1A48 4F46

xjMEY/NLpBYJKwYBBAHaRw8BAQdAOYWKZ1ra+QHIgD7ge2v+YI43XXBC5MARARS6
pOKDc8TCwAsEHxYKAH0FgmPzS6QDCwkHCRCvFqq4GkhPRkcUAAAAAAAeACBzYWx0
QG5vdGF0aW9ucy5zZXF1b2lhLXBncC5vcmcG865pH6HuZ4e/plCVfwDjNK7pp/w5
s+V4yNpdBeIKqQMVCggCmwECHgEWIQR9An5OfMaNqXq8R0yvFqq4GkhPRgAAzboB
AKfneg5xSCunNYEbY29WC60BmyeuLA8sJlCdBeXRbQPuAP40f8LUtla8WKrdVaaI
kKY5ToXrHG6+wnth46RjSz+GBg==
=TPwg
-----END PGP PUBLIC KEY BLOCK-----

keys.openpgp.org currently returns 500: Error: Error processing uploaded key. (also on VKS endpoint).

Is this the intended behavior?

The use-case would be users that want to share Keyoxide proofs on Direct Key Signatures and either don't care or are unwilling to share their e-mail addresses due to privacy concerns.

For the record I've generated the cert with the following code:

use sequoia_openpgp as openpgp;

use openpgp::cert::CertBuilder;
use openpgp::serialize::MarshalInto;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let builder = CertBuilder::new();
    let cert = builder.generate()?.0;
    let armored = String::from_utf8(cert.armored().to_vec()?)?;
    println!("{armored}");
    Ok(())
}