OED senses 9a and 9b, clearly show that, contrary to the AGU Grammar and Style, which you quote that due to can be used to mean the various things they say it cannot mean.
And note particularly the OED's comments that some authorities claimed, early in the 20th century, that it could not be used at the start of a sentence. This is now refuted.
It is, however worth noting that almost none of the examples given have it at the start of a sentence. It has clearly been considered, over time, to be an inelegant positioning. And perhaps for that reason objections are still made. Note that the one exception to this is the one from 1957, made by our present Queen.
- due to.
a. In predicative use: attributable to a particular cause or origin; derived or arising from; caused by, consequent on; as a result
of. Cf. owing adj. 3a.rare before 19th cent.; described by Johnson
(1773) as ‘proper, but not usual’.
1669 R. Boyle Hist. Fluidity & Firmnesse i. xxiv, in Certain
Physiol. Ess. (ed. 2) 196 The motion of the Oyly drops may be in
part due to some partial solution made of them by the vivous spirit.
1712 R. Steele Spectator No. 352. ⁋1 All this is due to the very
silly Pride that generally prevails, of being valued for the Ability
of carrying their Point.
1801 Monthly Rev. 35 537 M. De La Place..found the secular
equation of the moon to be due to the action of the sun on the moon.
1867 W. H. Smyth & E. Belcher Sailor's Word-bk. Driftage, the
amount due to lee-way.
1875 B. Jowett in tr. Plato Dialogues (ed. 2) IV. 136
The..difficulty in the Philebus, is really due to our ignorance of the
philosophy of the age.
1928 Daily Express 11 Aug. 7/1 Death was due to heart failure.
1967 Canad. Med. Assoc. Jrnl. 5 Aug. 286/1 Improved treatment of
diabetes mellitus in the past 45 years, due largely to the discovery
of insulin and antibiotics.
2007 A. Theroux Laura Warholic vi. 85 Much of the grit around the
stoveworks was due to his rather bad eyesight.
**b. As a compound preposition: as a result of, on account of, because of. This use become well established during the 19th century,
and is now usually regarded as acceptable standard English, but began
to be criticized in usage guides in the early 20th century, apparently
beginning with H. W. Fowler Dict. Mod. Eng. Usage (1926), which
described it as ‘often used by the illiterate as though it had passed,
like owing to, into a mere compound preposition’. Cf. owing adj. 3b.**
1840 Rep. Comm. Physics & Meteorol. Royal Soc. Antarctic Exped. 2
Periodical variations of temperature at its [sc. the earth's] surface,
due to the sun's position above the horizon.
1847 J. Craig New Universal Dict. at Arborized Agates which have
the ramified appearance of plants, due to the infiltration of water
charged with metallic oxides.
1897 S. T. Clover Paul Travers' Adv. 190 [The Koturah] was taxed
to her capacity, due to the fact that..she was advertised to go first
1920 Science 29 Oct. 406/2 Due to added medical responsibilities,
Dr. Hancock has now closed his Orthopterological studies.
1957 Queen Elizabeth II in Times 15 Oct. 10/6 Due to inability to market their grain, prairie farmers have for some time been faced
with a serious shortage of funds.
1978 A. North & I. Hogg Guns & Gunsmiths i. vii. 122 The earliest
multi-barrelled guns are known as ribaudequins or organs, due to their
similarity to organ pipes.
2014 B. Moran Making Marion vii. 68 Valerie had made me promise to
come along to Fire Night that Sunday, the last one having been
cancelled due to the sudden disappearance of Grace.