Allow or block OAI-SearchBot
User-agent: OAI-SearchBot
Disallow: /Asks OAI-SearchBot not to crawl any page. Well-behaved crawlers stop; it does not stop anyone who ignores robots.txt.
User-agent: OAI-SearchBot
Allow: /Lets OAI-SearchBot crawl everything. You only need this if a broader rule would otherwise block it.
Should you block it?
Keep OAI-SearchBot allowed if you want to appear, with a link, in OpenAI's answers. Blocking it is the fastest way to disappear from them.