Circular reasoning
Checking a known breached service (linkedin, pick your recent data breach occurrence) to see if users have had their data breached seems a bit redundant. It's the kind of lazy analysis companies do in order to come up with a headline reason why their staff are better than the randoms on a social network. Anyone using linkedin for longer than a few moments has had their profile exfil'd. Whether that is an actual problem depends on whether they are vulnerable to cred stuffing. Just saying someone appears on HIBP is weak research.
However putting clearance on your profile is a bit off. Clearance is for a specific purpose/role and does not carry to a new role. Hiring only those with current clearance is illegal (AGSVA site explains this quite clearly). And yet recruiters and employers do it all the time anyway. Which is why some are motivated to put their clearance in their profiles. Since what really matters to an employer should be whether clearance is attainable, perhaps candidates should put their citizenship and whether or not they have been to the big house?