Provided he had a good teleobjective and that his friend was in his closer surroundings (meaning same track and 1000ft above or below, some NMs away) he actually might have gotten his picture (provided this was the intention) completely legally and safe with an offset track (well, you start doing your offset while you come 'close' to your buddy). There are quite some pictures on the 'regular suspect' websites like that.
But any other technique is not really recommendeable and I have complete comprehension should this chap (or actually these chaps) have to find another income provider.