I would want to see a lot more in terms of positive justification, and/or endorsement from a significant and identifiable group of prospective users before I would consider myself comfortable with progressing this. So far, not very much has surfaced along these lines in the ongoing discussion. I don't find that very encouraging, and it contributes to my sense that this is premature - not because the characters can't be enumerated or named, but because of the uncertainty of the usage model and intended user group.
The situation is different from some other archaic scripts where neither the sets of symbols nor the languages that can be written in them are currently encoded. For those scripts, even if the scholarly community prefers to do its work in transliteration, encoding the script is necessary to allow representation of the texts as such, for whatever purposes that is desired.
In this instance, treating the earlier scripts as a style variation of a later script appears not only feasible, but would support a continuity in searching for material in apparently at least one of the important languages. By not separately encoding any of the earlier scripts, a technology based on (Hebrew encoded) fonts allows anyone to depict text in these scripts today, using the widest possible range of existing implementations, as opposed to having to wait for uncertain future support.
That to me seems a benefit that could outweigh the fact that, just as for Gaelic, or running Fraktur text, certain distinctions simply cannot be made in *plain* text.
No such solution exists for those archaic scripts, where either the range of symbols (e.g. hieroglyphics) or their layout behavior is sufficiently different from the modern script. For those scripts, the alternative therefore doesn't have to be investigated. However, for this script and its cousins, we cannot just point to dis-similar precedent or brush off the question. It must be addressed, and as John rightly noted, not just the conclusion but the supporting evidence and rationale must be documented.
A./
