This is a follow-up to a previous question of mine (Can you store a Spell Glyph with a spell scroll of a non-prepared spell?) where it was established that you do need to have a spell prepared in order to be able to spell glyph it.
This question is a slight twist to the previous one: if you do have the spell prepared, but also have a spell scroll of the same spell, are you able to make the Spell Glyph by using the spell scroll instead of a spell slot?
Ex: Bob the 5th level Wizard having "Haste" and "Glyph of Warding" prepared, and in possession of a Spell Scroll of Haste, willing to cast a Spell Glyph of Haste, but using the scroll instead of a spell slot, therefore only using a slot and a scroll instead of two slots.
A supporting argument for a "Yes" answer would be that the Glyph of Warding's Spell Glyph section does not mention the mandatory use of a spell slot for the spell to glyph, just that it must be prepared.
You can store a prepared spell of 3rd level or lower in the glyph by casting it as part of creating the glyph.