When I was flying in USAFE, there were standard ROE for jumping folks/being jumped when flying around Europe. Anyone could jump anyone they saw, but the fight was limited to one defensive move by the jumpee -- if that lost the jumper, that was it; if not, that was it, too -- no extended unbriefed air combat maneuvering permitted. It sounds from the press report like the Eurofighter may have slightly exceeded that rule by maneuvering to an offensive position once the Strike Eagles' offensive position was lost, but not by much.
However, a couple of air-to-ground loaded Strike Eagles would be no match for the highly agile and lightweight Eurofighter in a turning fight, which is as it should be, since the Strike Eagle's mission is night/all-weather interdiction, not air superiority, while the Eurofighter's primary mission is air-to-air. I'd like to see a Eurofighter carry as many bombs as far as a Strike Eagle can. Finally, the Eurofighter's technology is over 20 years ahead of the F-15 series -- match a Eurofighter with its contemporary F-22 Raptor, and you might see something really different.