Personally I wouldn't allow it because revivify just stops the body from decaying. In my world it's difficult to raise dead, revivify works because the spirit has not moved on yet. Once the soul has started it's journey, it takes a lot to get it back. I guess if it ever came up I'd have to make an official ruling since it also affects raise dead.
I've always viewed it as extending the Raise Dead spell because it specifically states that it doesn't restore lost limbs. If too much time has gone by, there's too much decomposition of the body to restore life.
You seem to be neglecting one word in the spell description. (I'm assuming you meant Gentle Repose when you typed revivify.)
PHB said:
You touch a corpse or other remains. For the duration, the target is protected from decay and can't become undead.
The spell also effectively extends the time limit on raising the target from the dead, since days spent under the influence of this spell don't count against the time limit of spells such as raise dead.
To me, "also" indicates that the time extension is in addition to the effects in the first paragraph, not a consequence of them. So my reading would be that
Gentle Repose does whatever is necessary to grant the time extension, including keeping the soul from moving on if that's what you think
Revivify requires. I suppose you could argue that
Revivify is not included in the set of spells "such as
Raise Dead" but that seems to me to require dragging in a lot of reasoning that goes beyond a plain reading of the spell descriptions.
All that said, adjusting spells that bring the dead back to life to fit your cosmology seems like a pretty reasonable thing to do (with the usual caveat that everybody knows about it upfront).
If one wanted to split the baby,
Gentle Repose could grant a shorter extension for
Revivify than it does for other spells that bring the dead back to life - maybe 1 day instead of 10.