All very good points.
I'm already questioning the John Haycock bap. 1774 Hordley being identical to the John marrying in Shrewsbury to Margaret Jones. You'd think the one baptized in 1778 in Sutton-by-Shrewsbury would be a more logical candidate, and nowhere in the marriage sources have I seen mention of the Hordley father Thomas. Of course it's possible at some point somebody researched the heck out of this specific tree,to come up with this connection, but to me that's a bit of a red flag.
Also, there are a lot of John Haycock(s) mentions in criminal records in the first half of the 19th Century, both in Shropshire and Staffordshire. A criminal past would be a good reason to obscure your background.
All in all this -again- won't be a walk in the park.
-EDIT-
After having plugged in 'my' 1816 John Haycock -who is confirmed to be my 2x gr.grandfather via DNA connections with both descendants of my gr.grandfather George and offspring of his half-siblings- in WATO, the strongest genealogically viable hypothesis continues to place me in the same branch of the family as my highest cM match, a man named Haycock from my mother's generation. This means I'll start with trying to source-confirm the Thomas Haycock & Mary Lythe tree via the branch of their son Robert (1782-1852) who married Sarah Bostock. My match descends from their son Robert (1808-1871). Age wise, my John could very well be a (half) brother.