I could only found nits in this I-D that shouldn't hold it from progressing:

0) Nits checker complains about the following line being to long in s5.3:

mail.client.example         CAA 0 issuemail "authority.example; account=123456"

can you do this:

mail.client.example
                CAA 0 issuemail "authority.example; account=123456"

Link breaks added for formatting purposes.

1) s/must not/MUST NOT in s6:

OLD:

If a Certification Authority does not
understand the Property, then it must not issue the certificate in
question.

NEW:

If a Certification Authority does not
understand the Property, then it MUST NOT issue the certificate in
question.