Currently all crawling is disabled; it's probably just some stupid default value, I can't imagine any reason why (it's all public logs, loading some static HTML can't kill a server).
Considering that labs services must not be relied on, at the very least you should whitelist the Wayback machine https://archive.org/about/exclude.php . I don't know if empty disallow or Allow: / is best.
User-agent: ia_archiver
Disallow:
Version: unspecified
Severity: enhancement
URL: http://integration-meetbot.instance-proxy.wmflabs.org/robots.txt