To answer the question: Yes.
Of course, it's not quite that simple.
Anyone with a modicum of ability and some ingenuity should be able to figure out how to install and set up a satellite dish. He shouldn't have too much trouble getting a signal.
However, getting the dish to the optimum azimuth and elevation without installers tools (satfinder) will require patience and a
lot of trial and error. Picture quality and/or the number of channels available will vary with the alignment of the dish.
The Sky Digital service is broadcast using several different satellite transponders (Astra 2A, 2B, 2C, 2D and Eurobird 1).
He will need a bigger dish to receive all the channels. The Sky mini-dish will get him some channels, but he will almost certainly want a larger dish.
The Astra 2D transponder is targetted at the UK only and carries BBC1,2,3,4/ITV1. A larger dish should be able to pick up the weak signal in Germany. Unfortunately, the SES Astra
footprint page suggests that he's on the fringe of coverage and will need a 120cm dish - difficult to install discreetly.
Finally, Sky insist that you connect your digibox to a telephone line. The box occasionally dials Sky to let them know it's still out there. The caller ID of the line tells them that the digibox is where it is supposed to be. They can disable the box over the air if they decide that it is being used illegally (no or wrong caller ID).
It is likely he will eventually get caught out by this, unless he can find a way of fooling the box into thinking it's still in the UK. There are companies out there who claim to get around this, but I don't know how true this is.
I am very surprised that Sky have suggested that it's ok for him to do this - it isn't. They normally get
very shirty about it. I'd ask for something in writing from Sky.