The 5D2 is more than 'a stop better', having shot primarily with both cameras and event shooting for the last year+. On paper, it may be considered 'a stop better', but in practical application, the image quality difference (and handling in low light) is apparent. I'll give you that a crop camera tends to hit the sweet spot of a lens, but depending on what you're shooting, that's not always the best thing. Sometimes you want a bit of natural vignette, or a bit of natural distortion. Portraits, for example, tend to look better on my 5D2 than they do on my 7D, because they have a different feel, based on the imperfections of using the majority of the lens. Also, depth of field is definitely noticeably different between the two. but we're going on and on here about 7D vs 5D2, and that's not what the OP was asking about, so let's go back to the 7D being too much camera bit.
Whether or not it's too much camera for someone is subjective. You could take someone like me that gets into something, invests money and starts with stuff that may be above my experience level temporarily, but once I get my bearings, I work into it and it suits my needs for some time. I could have saved some time and money by going straight into a 7D a couple of years ago instead of picking up a cheap Rebel to get a feel (ha) for the Canon system, before switching up to the 60D, before selling that to pick up my 7D. Our concern shouldn't necessarily be that it's too much camera -- in the hands of the right person, a $25 Holga is too much camera, but it differs from person to person. We should be addressing the questions of the OP, not comparing one camera that the OP is considering to another that the OP apparently is not.
Also, going back to the gist of the original question... if your dad is serious about it and ready to dump $2000 and you're in the US:
Canon 7D via Canon Loyalty Program (see link in my sig) is down to $1023.36 (plus tax and sending in an old broken or out of warranty Canon point and shoot, can he bad for like $5-$10 on eBay or thrift stores, or maybe even lying around your house).
Sigma 17-50 f/2.8 used - $400-500
Canon 70-200 f/4L non-IS used (refurbished with the 7D could be as cheap as 20% off of 567.99 which is $454.32 - you may even be able to find cheaper on Craigslist if you're patient and smart about it)
That should be right around the $2000 budget, and provide two great quality lenses, (one normal zoom, one telephoto zoom) that should keep your dad happy for a while..