True. Though Church rulings on whether the Levitical prohibition was natural or Divine law had varied over the years. See Kelly, op.cit.
And Henry resting his case on Leviticus was not a strong position. As Wolsey told him. And Henry ignored.
And for historical reasons that I pass over, the ruling was against Henry (hint: Charles V). But there was actually a stronger case lurking in Henry’s history (not that either case would have gotten him the decree of nullity; politics and military power trump canonical law). His stronger case, as Cardinal Wolsey saw, lay in a class of impediments called the justice of public honesty. Without getting into too many technical details, this meant that if a marriage was contracted and consummated between A and B, two actual types of impediments might arise for person C later wishing to marry A or B. That is, there was the potential for an impediment of affinity, which arose from the consummation of the marriage, or of the justice of public honesty, which arose from the betrothal/marriage contract.
At the time, the rule was that if a valid marriage was contracted, and consummated, and later a dispensation was sought for someone who would have an impediment to marrying A or B, the dispensation need only specifically state that the affinity impediment was dispensed, and the impediment of public honesty was thereby dispensed, implicitly. But, if Katherine and Arthur’s marriage was not consummated, as Katherine and her duenna maintained all along, and as was likely true, then the justice of public honesty must be explicitly dispensed. Julius didn’t do that. And hence there was a reasonable case for Henry in an undispensed impediment. Precisely the sort of crack the system was designed to allow.
He didn’t pursue that, and it didn’t really matter. Given the relationship between Clement and Charles, and Charles and Katherine, no way was Henry going to get a decree of nullity. An Emperor trumps a King. And an Emperor controlling a Pope is stronger still. So Henry didn’t get his decree. He got a Church, instead.
Politics/theology intertwined.