Threatening someone with fines or jail time, who took receipt of distributed but embargoed product, i.e. by no stretch of the imagination illegal to possess, is the sort of thing you might want to look into legal options for, though.
> 1a: a hostile or predatory incursion
> 1b: a surprise attack by a small force
https://www.merriam-webster.com/dictionary/raid
alternatively wiktionary:
> raid (plural raids)
> (military) A quick hostile or predatory incursion or invasion in a battle.
> An attack or invasion for the purpose of making arrests, seizing property, or plundering.
https://en.wiktionary.org/wiki/raid
Raid seems like the perfect word for this. Though the headline could make it a bit more clear that no police were involved
If the PI brings a bunch of big goons with guns and they imply that they'll kill you if you don't turn the thing over, then sure, that's a raid. But also you'd presumably call 911 immediately and file a police report stating that you were robbed.
That the attack depended on surprise and intimidation doesn't invalidate the use of attack or raid imho, that's the preferred outcome of any police raid too (and websters definition of attack is "to set upon or work against forcefully", no mention of physical violence).
A PI who's even vaguely trying to obey the law DEFINITELY does not expressly threaten you with violence, and won't allow any more than the barest implication either.