If the guy keep paying mortgage for years, or until hosing market recover, you can then forclose it, because there is some equity in it.
So, sooner or later, you can get all the money due for the HOA.
Either way, HOA really has no need to actually forclose it.
Threaten it would do the job. If he does not care, it means no equity in it and it will not do any good for hoa with forclosure.