From the Biki:

blacklistPos (Optional): List of blacklisted areas in format [area1, area2, area3... areaN] (Default: []). Area could be one of:

• Array - in format [topLeftCorner, bottomRightCorner] - top and bottom coordinates of blacklisted area
• Object - trigger area
• String - marker area
• Location - location
• Array - array in format [center, distance] or [center, [a, b, angle, rect]] or [center, [a, b, angle, rect, height]]

The last two alternate blacklist array formats appear to be incorrect. Using them returns a blacklist area not reflected by its parameters. The error(?) is in the extra set of square brackets around the dimensional params - [a, b, angle, rect]. If those brackets are removed, the blacklist is processed correctly.

Discussion on the BI forums here: https://forums.bohemia.net/forums/topic/228203-bis_fnc_findsafepos-blacklist-options/

Either this is a bug, or a simple misprint/error on the Biki. I am assuming the latter.