I believe that post pre-dated the existence of standard rules artillery. The answer applies specifically to advanced rules artillery, as it was all that existed at the time.
In advanced rules artillery, indirect fire artillery only uses the to-hit modifiers listed on p75. Indirect does not use range bands, target type, target movement, terrain, etc. Even if the spotter is spotting through woods, in smoke, while jumping, none of those modifiers on are on p75, so they don't apply to indirect artillery. So attacker movement does not either. That's for onboard or offboard.
Advanced direct fire artillery says to use p75 modifiers, but also says to include intervening terrain, target type, target movement, etc. So with the addition of attacker movement modifiers to Alpha Strike, I ruled direct fire should also add that to the list that affect it.
Standard rules artillery works as much as possible like standard attacks. Attacker movement modifiers work the same as they do for non-artillery standard weapon attacks and indirect (LRM) attacks, ie. attacker movement modifiers affect it.