I'm not sure that logic works. You're assuming that the Ads are matched to the query in the same way that results are matched to the query - that a more restrictive query necessarily translates into fewer ad matches.
There's another possibility which is that the ads are the query and the search query is in fact their match result. In that case, adding or removing quotes within the search query might not have any impact on the ads being shown.
Don't know which way it works, but it seems to me the latter would be better for showing ads without having any negative impact on search results.
There's another possibility which is that the ads are the query and the search query is in fact their match result. In that case, adding or removing quotes within the search query might not have any impact on the ads being shown.
Don't know which way it works, but it seems to me the latter would be better for showing ads without having any negative impact on search results.