Non sequitur alert. The descriptive is not proscriptive. The factual observation that "God is beyond the purview of science" does not entail the He is "not allowed". He is certainly allowed. Go ahead and develop a God-based or God-inclusive scientific theory (if you can) that really works and you will have thereby expanded the purview of science to include God.
Unfortunately you can only do this by ACCOMPLISHMENT, not by DECLARATION. IOW you can't appeal to the saying-makes-it-so word magic that the radical left, and other insane people, resort to. The purview of science is determined by the content of science, and the content of science is determined by what scientists actually DO (not what they may say or declare) that is by what ideas working scientists actually utilize and implicate in the production of original research.
To put it more simply, the "purview" of science is determined by the reality of what science actually is. So if you think there should be a "God-inclusive" science then SHOW US that science, or continue to whine pointlessly. There is no in-between.