For readability, I suggest ignoring all of the lengthy comments, which have no force of law, and focusing on the amended rules towards the end, which do. This is the only text that will appear in the Code of Federal Regulations. See pages 705-706 of the final rule issuance document, which states, in pertinent part to this discussion:
§ 65.109 Repairman certificate (light-sport): Privileges and limitations.
(a)
The holder of a repairman certificate (light-sport) with an inspection rating may perform the annual condition inspection on an aircraft:
(1) That is owned by the holder;
(2)
That has an experimental airworthiness certificate issued in accordance with § 21.191(g), (i), (k), or (l) of this chapter; and
(3)
That is in the same category, and class as applicable, of aircraft for which the holder has completed the training course specified in § 65.107(c) of this part.
That is my point, but you have to look at the sections cited to understand who is eligible. As quoted above, you have to satisfy parts (a) and (b) and (c) to get the new CI privilege. Right? I think we can all agree on that, including subsection (a)(2) requiring "That has an experimental airworthiness certificate issued in accordance with § 21.191(g), (i), (k), or (l) of this chapter."
21.191(i), (k) and (i) do not apply to EAB, so for owners of aircraft certificated as EAB the only way to get the new CI privilege is to satisfy and hold an EAB certificate issued under 21.191(g).
21.191(g) states that only the aircraft's builder can be issued a 21.191(g) cert. We all can agree on that.
So here is the source of the interpretation confusion - we can read the 21.191(g) requirement in 65.109(a)(2) quoted above to mean either:
1) anyone who currently holds an issued and valid EAB certificated plane, which of course includes people that did not build the plane and later the purchased the EAB certificated plane; or
2) the phrase "in accordance with 21.191(g)" limits the scope of the new priviledge to only those people who built the plane, because they are the only people who can receive an EAB certificate "in accordance with" 21.191(g). People who subsequently buy the EAB have a valid 21.191(g) certificate, but it was not issued by the FAA to the new purchaser "in accordance with" 21.191(g) - it is transfered to the purchaser by the person who built the plane, requested, and was issued the 21.121(g) EAB certificate by the FAA.
As a lawyer, I am sadly 95% in the #2 camp because of the plain language and comments (especially footnote 279 I quote below).
I am sure you are asking why the does the plain language support interpretation #2? It is because if the FAA wanted to apply the new privilege to anyone who merely possesses an EAB certificated plane, the FAA would have applied the requirement in 65.109(a)(2) to an owner of an aircraft "That has a § 21.191(g), (i), (k), or (l) experimental airworthiness certificate"). Instead, however, the FAA limits is to only those "issued in accordance with."
The FAA comments from 430-36 (yes, six long pages with footnotes) under the title "Expand Repairmen (Light-Sport) Privileges to Include EAB Aircraft Under § 21.191(g)" explains that the expansion is limited to 21.191(g) certifications. In particular the FAA states in footnote 279 within the six pages that the expansion of the CI privilege makes sense and is supported, in part, by the fact the builder issued the EAB in accordance with section 21.191(g) certificate has special knowledge and skills based on the fact the person built the aircraft and made express represenations/evidence to the FAA about their builder status in order to get the 21.191(g) certificate:
"An individual who shows to FAA evidence of building the major portion of an aircraft are eligible to
obtain a repairman certificate (experimental aircraft builder), with privileges limited to the aircraft that
person has built. FAA considers these individuals to have demonstrated acceptable knowledge of the
aircraft and able to perform a condition inspection
because the individual built the major portion of an
aircraft that was found safe for flight by FAA and subsequently issued an airworthiness certificate"
I would love to be wrong, and granted that I am not 100% sure, but it appears to me that the new CI priviledge w/training does not extend to anyone and everyone who merely who owns a 21.191(g) EAB certificated plane. What really tips it in for me is footnote 279.