The reason for bolting is to make later replacement easier, by avoiding the effort of grinding off the old welds and welding again. To change from welded to bolted (using the Dexter side-mount bracket) would mean grinding off the just-done welds, welding on the bracket, and bolting the axle
Since I don't see an advantage to expending that effort now rather than maybe
later - except that the fabricator might absorb the cost - as long as the axle
is properly mounted I would just leave it.