Yea, doesn’t look like they nabbed any Americans. But this will likely kill recruitment of foreign nationals. I have the same question you do - why admit to this and why do it now (Hezbollah allegedly busted up this spy ring back in June)?
Its a shady world, but I’d like to think it was done as damage control for the right reasons... If we KNOW they have clear evidence of our involvement, especially something that may reveal our personnel, methods, etc., it may be better to just say yeah they were ours while we try to influence...