Any such passing would doubtless include a hail of Oort debris . . .
...as if finding a local brown dwarf was not enough...
As the report states it to be a failed star, I would set the probabilities of such a passing to be similar to the last time a full-blown star came too close to our Sun. As stated in my "If" post:
"WISE and Spitzer, and all others capable, will need to track this bit of flotsam to chart it’s proper velocity, to be checked against that of the local neighborhood."