Write access is a subset of all access, so I don't think we can really argue that the plain meaning of the original statement was about removing write access.
But yes, a missing word is certainly a plausible explanation for how they issued a statement that meant the opposite of what they apparently intended.
But the original statement did not say all access, it merely said access:
> During that period you will maintain access to any of your public images
Assuming that the you in that sentence is the organization and not the general public (given the use of your organization earlier in the paragraph), the logical interpretation is that they meant write access here, and not all access -- since read access is not limited in any way to the you in that sentence.
Yes, I agree the original messaging was terrible. But claiming that the original can only have meant all access is not consistent with the wording of the announcement.
But yes, a missing word is certainly a plausible explanation for how they issued a statement that meant the opposite of what they apparently intended.