Ambrose V Pakistan and India at home is a measurable category, therefore we can make an assessment of the category. How much meaning is attached to the category is up to the person making the assessment. Another way of looking at the figures is to say that his bowling was ordinary during 17 Test matches against Pakistani and Indian batsman.
HowSTAT! Player Analysis by Country
HowSTAT! Player Analysis by Country
A similar example, but in a batting context, would be as assessment of Dennis Compton's tour of Australia in 1950-51 where he scored 53 runs in 4 Tests at an average of 7.57. To some people it is enough to remove him from the Gold Tier level, but for others it has less meaning. They simply say, like you did, that he was successful against Australia overall, and had other good tours of Australia, so what does it matter?
As I said before, I'm not concerned about Curtly's home record against Pakistan and India for reasons similar to yours, and therefore still have him in my Top 10. But those stats still look ugly when taken at face value just the same.