As you say, it's a slightly unusual career progression, but not impossible, especially given he'd changed country and different skills might have been in demand in Australia, and have paid differently, than in Yorkshire.
I'm no big expert on WikiTree, but I can't see it causing any problems if you make profiles for the Huddersfield family assuming there aren't profiles for them already. The only exception is James, since he might be the same as your ancestor and we're supposed to avoid making duplicate profiles of the same person in as far as possible.
At the end of the day, there is a certain amount of guesswork in most pre-1837 English genealogy unless the family was rich and left more records than most (if John Johnson was married in village X and there was a John Johnson christened in village Y nearby, was it the same chap or did he in fact move halfway across the country to end up in village X instead?). So it seems to me that unless someone else is particularly interested in the family and has their own view that might differ from yours, it's up to you to decide how much evidence is needed to connect your profile as the child of the Huddersfield family. Probably, as you say, on the current amount of evidence it's more sensible to connect him via notes that explain the evidence and the doubts. If someone else is interested in them, you'd need to come up with a consensus view with them on what to do.
I had another quick look just now - it looks like the mother was still in Huddersfield in 1881 (https://www.familysearch.org/ark:/61903/1:1:Q27R-2HRM
) - unfortunately you can't see on FS who she's living with! It might be worth checking if you can do that easily, just in case it's her son James with his name garbled. Also I can't see a death registration for him in Huddersfield between 1871 and 1881.
I'm not at all familiar with Australian records - is it unusual for the parents not to be named in a marriage record, and do you have any idea why that might have happened if it's not usual? In English records, the father was normally the only parent listed and if his name was left out then typically it was because he wasn't married to the mother, and lots of times I've seen examples in the registers where a vicar has written the father's name (or started doing) but then crossed it out when he realized the parents weren't married. Other vicars were happy to write the father's name in regardless, which was much more helpful to us.
Another thought - is there any chance a local paper might have published an obituary for him when he died? I've seen some American ones that were amazingly detailed and helpful.