Lock is Parker's ideal position. You basically get the best of both worlds in that Parker still has to work in the middle but has the luxury of not being relied onto manufacture momentum, which suits Parker to a tea.
The only position I'd consider shifting Parker to is on the fringe. Usually, Parker is pretty useless close to the line, but for the Maroons he actually looked quite threatening. If he could have passed sooner instead of relying on risky offloads (which thankfully paid off) he could be really deadly, especially at club level. Mind you, I'd only consider that option if our backrow wasn't at full strength, I rate Glenn and have faith in Gillett.