Direwolf - your massive xp munchkin has two flaws which a sadistic SG can easily abuse.
1> they're not apprenticed until they're 35. Another magus can offer to take on the apprentice and legally the apprentice is theirs. (This is suggested as a more heart-wrenching story seed in one of the books where someone takes an apprentice who is the child of a magus in your covenant). In fact, IMS gangs of known sadistic Tytali would probably descend on your covenant looking for such a candidate apprentice.
IIRC, sometimes Gifted people whose gift isn't opened to a magical tradition start spontaneously developing Supernatural Virtues, which causes problems for those trying to open their arts. (This is mentioned in Hedge Magic.) Under the circumstances, if the SG sees your InVi lab total isn't that high, they might give your gifted child a major supernatural virtue as a coming-of-age present...then start adding more virtues (and corresponding flaws) every time it looks like you might be able to open their arts.
2> a bonisagus could go "Wow! That's the best apprentice I've ever seen!" and take it from you. Even worse, if you have a player character Bonisagus in your covenant they'd probably do it deliberately.