I think all Ven. Analayo is saying is that he think the garudhammas were laid down before the other rules on ordination found in the bhikknunī-kkhandhaka. I don’t think this means that the garudhammas need to be accepted by a female candidate before ordination.
There are several points here. The first is that VA distinguishes between a historical/text-critical reading of the texts and a Theravadan legal reading. It is only on the legal reading that the garudhammas were established before the other ordination procedures. So if a female candidate feels there are strong historical reasons why the garudhammas were not laid down by the Buddha - and she does not really see herself as a dyed-in-the -wool Theravadan - then I think she can still cogently argue that she will/should not keep them.
The second point is that even though VA is giving the garudhammas temporal priority over the other ordination rules, this still does not mean they were laid down by the Buddha. Much of bhikkhunī Vinaya is quite late, and I cannot see any good reasons to think these rules come from the earliest period. For me it seems quite likely that these rules were not laid down by the Buddha.
The third point is that the garudhammas are, as VA puts it, just injunctions. In other words, they are minor rules, and there is no penalty for breaching them. If you look at the sekhiya rules of the pātimokkha, you only breach them if you don’t keep them out of disrespect. This means that if there is a good reason for not keeping these rules, such as a change in culture that makes the rules obsolete, then there is no penalty for not keeping them. In fact, I would go so far as to say one should not keep sekhiya rules that are no longer sensible. The same, in my opinion, is true for all the minor rules found in the Vinaya, including the garudhammas. These rules do not need to be kept if they are out of synch with the prevailing attitudes at any time and in any culture. If they are kept, they just tend to make Buddhism obsolete and to destroy its credibility.
In sum, I fully agree with Bhante Sujato that there is absolutely no reason for bhikkhunīs to keep the garudhammas, except, of course, where they are also found in the pātimokkha. In fact, I too would recommend bhikkhunīs not to keep the garudhammas. Keeping the garudhammas is bad for Buddhism.