I wonder what Twitter-ID he means. Is there an API to get a numeric ID for a given handle that stays the same even when you change your username? If he means the username, wouldn't it be possible to programatically change the username after each request and thus avoid the throttling?
https://dev.twitter.com/docs/platform-objects/users
EDIT: After rereading your comment you might have been asking if it was possible to retrieve this id with a simple API call and not with OAUTH. It is possible with "users/show" as explained here: https://dev.twitter.com/docs/api/1/get/users/show
"BlinkLink managed to get about 50k pageviews against 17k visitors"
I'm not sure on how much other sources (Reddit, Twitter) contributed to that number though.
You can roughly estimate the amount of visitors on a front-page HN post by 1 point :: 100 unique visitors. In this case, (17k visitors on 138 points), visitors viewed the page 3-4 times, which is unusual.