To obtain the correct chain line (when the hub has been re-spaced), and assuming that the wheel is dished correctly, will not be as strong as a 130mm hub with a freeHUB
You are precisely wrong. Converting a freehub to singlespeed doesn't, indeed cannot, change the dishing, so it remains as weak as a normal geared hub. Flipping the one long spacer on Campag threaded freewheel hubs to the other side gives a close approximation of a good singlespeed chainline and results in an almost dishless build, i.e. with a much improved bracing angle on the drive side, better tension balance from side to side etc.
You are precisely wrong. Converting a freehub to singlespeed doesn't, indeed cannot, change the dishing, so it remains as weak as a normal geared hub. Flipping the one long spacer on Campag threaded freewheel hubs to the other side gives a close approximation of a good singlespeed chainline and results in an almost dishless build, i.e. with a much improved bracing angle on the drive side, better tension balance from side to side etc.