It doesn't matter how broad his interpretation of the word 'widow' was, if John Ward wasn't dead, Judith wasn't free to remarry, and all three involved could go to prison. The first prosecution for bigamy occurred in N.S.W. in 1818 and you'll find many cases on Trove. These three weren't dishonest people, and there's no way they would have broken the law that way.
There are many many instances of NSW marriages where it would seem to 21st century eyes that there ought to have been a civil prosecution for Bigamy, yet there was not. Further investigation usually brings the family history buffs to the various statute laws of NSW, and for the usual meaning of the word 'widow' and the NSW marriage Acts. Trove is an excellent resource, and I draw your attention to Lachlan Macquarie's general orders that were frequently published in the Sydney Gazette. In particular, one (of many) regarding marriages... It remained in effect until 1 March 1856 and the introduction of civil registration.
https://trove.nla.gov.au/newspaper/article/627938 3 March 1810
Of course, the English statute laws had no effect on NSW from 19 July 1823, unless the particular statute expressly defined it to be effective in NSW, as per Sir Francis Forbes determination as Chief Justice of NSW.
I think you will find that one of the first prosecutions in NSW for the civil crime of Bigamy was earlier than 1818. I have info on a guilty verdict in 1816 for an offence dating from early 1815. I think the male got 3 years H.L. at a secondary penal settlement, and time in gaol. I have other examples where no charges were laid despite the newspapers noting the police had been notified of an apparent bigamy.
Perhaps there's some useful info at the following thread
https://www.rootschat.com/forum/index.php?topic=648372.0which mentions an update to Henry Finlay's paper
https://webarchive.nla.gov.au/awa/20050804235330/http://pandora.nla.gov.au/pan/34360/20050715-0000/www.aifs.gov.au/institute/seminars/finlay.htmlMay I please ask how you know with certainty that the John MAXWELL aka John WARD who died aged 36 in 1853 was the chap who married Judith REECE? And also
who (oops, edit to

) how do you know with certainty that the Judith WARD who married in 1855 with William McKENNA was the widow of that same John WARD?
By 1853 Wellington Valley was a popular transient locality ... afterall there had been the 1851 discovery of gold on the Turon which then joins up with the Crudine and then flows into the Macquarie, and Wellington is one of the towns along the Macquarie. Those western goldfields were overflowing with people from various places around the world. The population of NSW increased from less than 200,000 to more than 350,000 between 1851 and 1856.
JM