That's because they're simpletons who don't understand how to circumvent the issue (well, it's Guitarworld so what do you expect). Certain wireless units have stereo jack plugs which are how they're charged (not the vast majority of Line 6 devices). Active basses almost always use a stereo jack socket in order to switch them on - the ring and sleeve are connected to ground and battery negative respectively. I think these rechargeable bugs will work with basses which are wired one way round (eg. ground to sleeve and battery negative to earth) but not the other way round.
Ah, just found this on the page for the Boss WL-50: "*1 The typical TRS output jack wiring of guitar active circuit is audio to tip, ground to sleeve, and battery ground to ring. In rare cases where ring and sleeve are wired reversely, the guitar active circuit doesn't work properly with the WL-T." - https://www.boss.info/uk/support/by_product/wl-50/support_documents/eade711c-1f5a-4951-988b-e8e863611c64/
There are two ways to circumvent this, if you have an active bass which is incompatible with the bug. The first method is simply to switch the wires to the jack socket over. This does require very minor surgery on the bass - anyone who can wield a screwdriver and soldering iron without impaling themselves and suffering third degree burns can manage it. The other is to get a short extension lead, mono jack socket to mono jack plug, plug the wireless into one end and the other end into the bass.