Taking a case to the SC is not as easy as you seem to think. Except in very unusual circumstances (like the 200 election) the SC moves at a pace that makes a snail look positively speedy. They are frequently outpaced by growing grass.
First a case has to wend its way through all of the lower courts most of which are extremely reluctant to void a law on constitutional grounds, then the SC has to agree to take the case.
Now think long and hard about this next one: before taking a case to the SC you have to be certain it is the right case. Just like asking the General for a decision, you will get a decision from the SC. If the case you choose to take there is weak, you may get the wrong decision, and the SC will not take another case on the same or even a very similar issue for the better part of a century.
Ashcroft has had the opportunity to ask the SC to take a couple of 2A cases and has decided that he would rather wait for a really good one than go in with a weak one. I think one of the cases may get there without him & in that instance he will support the individual right interpretation.