That isn't how computers or mathematics work. If you calculate an average or perform other simple statistical methods it is impossible for the results to be Turing complete. If they used some hypothetical recursive Turing complete method of analysing the numbers then the mathematicians would be aware of it being Turing Complete. Even if such a analysis was performed the alien program interpreted it would be only to affect the results of the analysis and not the computer as a whole because a mathematical analysis doesn't require network access, disk access or the ability to execute machine code.