My OH says it's just a polite way of turning us down,
I don't think that is accurate.
There should be huge movement.
There will be many candidates who have applied to multiple independents... they can only go to 1.
Depending on the area, there may also be many GS candidates who are using Independent as a backup, these candidates are likely to be turning down multiple independents if their GS option comes off; given they are likely eventual GS candidates they will probably have passed the academic selection phase for the independents.
Being on the reserve list is good; but there is no way of knowing before March 2nd + a week or two how the lists will behave; people who are holding offers also often defer their decision as late as possible in case their circumstances are subject to change etc.... not nice for those waiting.