Uncapitalized @top rule not working?

I’ve learned that uncapitalized terms will not appear in syntax tree, but why this is not true for @top rule?

I have this:

@top program { A }
A { "a" }

I expect to get A, but still get program(A). Why?

Top nodes are special—since they form the root of the tree, they can’t be hidden.

OK. Thanks.