I have no experience of SS or DT, but Alamy's standards are quite a bit lower than iS's used to be.
You can't pass initial assessment based on the lower news standards.
It used to be that you had to be invited to submit via the News channel. That may have changed since I got my invite, but I think it's still needed to get to submit via FTP.
If your camera can handle noise well, why not up your ISO?

Four other things you might not know (apologies if you do)
1. News must be uploaded within 48hrs, and it may now be 24h (?). Tbh, unless you're the only person seeing the news event breaking, Alamy isn't the best outlet. If the event is pre-planned, newspapers will have people there, and even if not, they often prefer a free pic a reader has sent in via paying. The first thing I submitted as news photos*  was illustrated in the local paper by pics of a much worse quality than I'd have got on my pre-smartphone phone's camera.
My own experience is that I haven't sold anything directly via their news channel, but some have sold afterwards as secondary editorial. But because I up my ISO if necessary, I'm sure all my news pics would meet their normal standards.
I'm not sure how long has to elapse before pics can be counted as archival.

2. If uploaded via the News channel, there is a note on the file page to say that the standard of the pic may be below normal acceptance standard, which may put buyers off.

3. If you are already submitting editorial pics to e.g. SS, you can't send the same pics to Alamy. If you don't have releases (for which they are much stricter than the micros), they must be RM on Alamy, and they don't allow us to sell images RM there which are being offered for sale as RF elsewhere.

4. If, like me, you'd find Alamy's 'manage images' a PITA, there's a double whammy, because the caption is searchable. For example, say one had a photo of "a large crowd waiting to see the Queen and Barack Obama", that phrase would be a necessary part of your caption. However, as the caption is searchable, the pic would show up in a search for e.g. Queen or Obama, so after a while (a week or two) I go back in and alter the caption, putting that sort of information into the description field which isn't searchable.

*purely local interest, but Alamy told me they'd submitted my pics to the media local to me, as they'd had to phone me re an issue (they were telling me off because I hadn't sent them all in one batch as is required. As it happened, I tried to, via their usual upload system, and random files kept failing and I had to keep resending, resulting in different batch arrivals).

I also have a lot of pics of political rallies which I shot as an election observer in developing countries. Some of them are really rare, as elected african presidents and politicians campaigning in rural areas or at mass campaign events. Given the difficult conditions, the pics are not always tack sharp or perfectly composed and I also have noise on them as these events are held usually at the end of the day or early evenings.

Although these pics were accepted with no exception on Alamy, I gave up with them since they never sold. Since then I have them on IS, DT and even SS, sometimes I had to explain SS the editorial value of the images and then they got accepted. So I gave up on get them in breaking news sections - I guess news portals have their own sources - but I have sold many of these images weeks or months after the events. I have a picture of a political rally in Uganda from the 2011 elections which is selling 2 or 3 times a week as an illustration of articles about african politics. So maybe is not that bad having them on microstock sites.

As an alternative to Alamy I can also recommend demotix.com specialised in photojournalism, or you could also take a look to Newzulu partner to Alamy and Getty Images.

I would say the standard needed at alamy is way lower than SS or even DT - don't submit shots taken in difficult conditions for the test - use 4 technically good ones cos that's all that matters to them.  Personally, I wouldn't sweat it as sales, even if they fetch a much higher royalty, are like hens teeth.