Ally spirits in animal bodies, Not sure if I'd allow it Options

[Deadeye]

One of my players-to-be has created a pretty wiz little hermatic with a great backstory. The character had a childhood disease, so his physical stats are limited (via the Infirm flaw), but he also had some bioware installed as a result (I allowed a little cultured bio because it fit with the character's story of being a semi-bedridden accademic). Originally, he had planned to have a level 3 Power Focus to start out, to offset the loss of his Essense/Magic, and, again, it fit with the character concept.

Then he borrowed MitS.

Suddenly, he has the idea of investing an animal with a Force 3 or 4 ally spirit, probably 3. He also happens to be a big R.A. Salvatore fan, and wants to have the animal be a Panther. Hold on, says I, you can't drag a panther around the sprawl with you. "Well how about if I learn the Shapechange spell on its behalf? Or create a limited version of the spell (he's got spell design 6) that allows her to change into human form and then learn it for her?" Let me get back to you, I said.

So. The closest I could come to a Panther is the critter stats for a tiger. Assuming that he just goes with a Force 3 ally, though technically he could do a force 4, the physical stats alone would break down like this (shapechanged human form in parenthesis):
Str 11 (3)
Bod 11 (3)
Quik 8 (3)
Cha 6
Int 9 (the mage has got bio and an exceptional stat merit)
Wil 6
Reaction 8 (6)
Init 8+3d6 (6+1d6)
Attack of 10S +1 reach.

This doesn't take into account skills and such that he might buy for it, but lemme ask a series of questions:

Should I allow this? I want to, because a physically weak character having a "bodyguard" sounds good within the confines of the character, which is always a big thing for me.

Can his ally have the shapechange spell bought for it right off the bat, and if so, what force should I insist that he take it at?

What are the advantages/disadvantages of having an ally spirit in a form such as this, beyond the normal problems and benifits one gets from an ally?

I'm leaning towards telling him that I'll allow this, but not at character creation; maybe as part of initiation if he ever does it. I don't think he realizes how big a deal only having 4 magic points will be. Thoughts?