Except you only have to be able to meet the time requirements and then the quill takes that time in your place. You don't have to sit around doing nothing, you just have to have had the capability to take the time needed to craft the scroll, even if you never actually had any intention of taking that time.
By that logic, you can't activate the quill if you have less than eight hours left to live. Which is clearly not the case.
Anyway, let's investigate the exact wording
You can use this skill to read a spell or to activate a magic item. Use Magic Device lets you use a magic item as if you had the spell ability or class features of another class, as if you were a different race, or as if you were of a different alignment.
"Treat this just as if you were scribing it, including gp cost, XP cost, time, and all other construction requirements.
The quill writes
as if you were scribing it.
Use magic device allows you to use the item
as if you had the class features of a wizard.
The "you" that the quill sees is a wizard, not a twelfth level warlock or whatever.
Scribing the scroll is part of (indeed, the whole purpose of) using this magic item. I don't see why the quill should 'pierce the veil' any more than any other magic item.
For example, take the Holy Avenger
Holy Avenger
This +2 cold iron longsword becomes a +5 holy cold iron longsword in the hands of a paladin.
It provides spell resistance of 5 + the paladin’s level to the wielder and anyone adjacent to her. It also enables the wielder to use greater dispel magic (once per round as a standard action) at the class level of the paladin. (Only the area dispel is possible, not the targeted dispel or counterspell versions of greater dispel magic.)
Strong abjuration; CL 18th; Craft Magic Arms and Armor, holy aura, creator must be good; Price 120,630 gp; Cost 60,630 gp + 4,800 XP.
Let's say a tricksey rogue picks it up, and manages to make the check to convince the holy avenger that he's actually a level 20 paladin. If he uses the greater dispel magic ability, it's going to be a CL20 greater dispel magic (since he's emulating a level 20 paladin), and not a CL 0 greater dispel magic (since he has no paladin levels).
Basically, all of the item's effects should be treating you as if you were a member of the class. You can't pick and choose.