Fluorescent bulbs are coated with a powder called phosphors. The "black lights" do not have these. Instead they have a purple colored glass.
The idea in a regular fluorescent bulb there is usually Mercury vapor that emits UV
light when in a high energy state. The UV
light emitted is absorbed by the phosphor coating on the inside of the glass. The electrons in the phosphors begin to tap dance around the atoms and re-emit light in the visible wavelengths. The wavelengths emitted depend on the phosphors used. The UV
really does not make it through the bulb.
Your friends blacklight does not have these phosphors and therefore is emitting in the purple visible spectrum ( a little bit), but mostly in the UV
range, which you cannot see. Most blacklights emit in the UVA range which is the least energetic of the UV
Will it be the same as Actinic light - no.
Will it harm the critters - possibly.
Will it be beneficial - I doubt it.
Hope this helps you to explain it to your buddy.