How do you get enough leverage to move and try and lift something off you by its edges when you are face down and have spikes petruding from every side but the ground side? Your also in a box with very little light, stuck looking down more or less, and I should also have pointed out the box he was incased in appeared to be made of the same stone the dungeon was made out of, stone is pretty heavy. He essencially couldnt move a hare without in his mind being sliced and poked.
First off, prone is not face down. Nothing in the description of prone indicates that. So most of the rest of your argument falls apart when you replace the prone condition with the "prone and restrained" condition. Your elaborate description is one of preventing the target from moving (or in most cases acting) at all.
Minor Illusion does not have that level of power.
Secondly, your description here is kind of funny. You make a box of stone. If Minor Illusion stops light, then the target cannot see the box, the spikes, or anything else and just stands up. If Minor Illusion does not stop light, then your description of "in a box with very little light" is invalid and not a feature of Minor Light (see this thread).
Minor Illusion and Light
And razor wire??? Seriously? Your DM allowed that in a D&D game? Barbed wire was not invented until 1867 in the real world and razor wire much later than that. How would a medieval wizard even know what razor wire is? Does your DM allow ray guns too?
Quite frankly, Minor Illusion does not have the "restrained" feature, so it doesn't get it. Just like Minor Illusion does not give advantage. There are some circumstances where Minor Illusion might give tactical advantage or even advantage for PCs on one side of it who know it is an illusion firing arrows through it, but a DM would be reasonable to state that arrows coming through an illusionary door is the same as interacting with the illusion and the PCs cannot keep doing that for multiple rounds.
It's a cantrip dude.
I'm all for the players being creative, but there should be limits to that. No Web spell equivalent for a Cantrip.
A player can make a chest, a chair, a pile of gold, a door. But razor wire surrounding the NPC (prone or not prone) is something that the NPC should get out of right away IMO.
Creative? Sure. But no way as a DM do I allow a cantrip to hand out the Restrained condition with no saving throw.