Not sure what you mean by that. A substantivalA substantive rendering doesn't negate an attributive rendering, but reinforces it, as in 1 Pet 5:10.
It's interesting that in 2 Cor 11:31, ὁ ὢν is tranlated by Trinitarians as "He who is" but in Rom 9:5 it is translated as "who is," in order to pre-emptively thwart an association between ὁ and Θεὸς.
This suggests pre-emptive English renderings are being used to manipulate Greek renderings to create ambiguities where none would exist if the substantival "He who is...." were to be pre-emptively retained, and which is always justified on technical grounds where an article precedes a substantive.
Changing "He who is" over to "who is" is only permissible for English stylistic reasons, and not to predetermine the Greek rendering.
Thus "He who is above all God blessed for ever" ==> "God who is above all blessed for ever" is permissible because it relates only to English style and retains both the Greek substantival and attributive senses.
But dropping the "He who is" down to "who is" just to bring Christ into the doxology is inadmissible, as an obvious attempt to ma
function of a Greek adjectival participle is a quite different function than an attributive function of the same.