As you can guess, it's really debatable.
Aside for the legal and combative arts question - will it actually back off a potential assailant? It's tricky - if the perp has their own weapon, it could actually escalate the situation. If you took it all wrong, it was just rough talk from a tired guy beaten down all day, now you're attacking his mental self image just the way yours was. He may get ticked and wrongly decide to thump you anyway.
Experienced hoods may just laugh - they grew up with violence and passed throught the knife stage to guns at thirteen. If he's already decided you are keeping him from his next fix, it may just set off his decision to act with a focus on extreme violence to get what he wants.
You can't really read their mind to see what level of force you need to equal. Firearms always have the trump in this scenario because you can literally reach out and touch them beyond their reach. Knives are woefully inadequate in this regard - and they have no immediate stopping power. Sure you could cut the guy, but that may be acceptable at this point. Cuts heal - scars are badges of honor.
Overwhelming intimidation requires imposing something they can't deal with, such as firearms, or a cell phone with camera. Taking their picture may set them off anyway, but if they are at all capable of a little thought, they know heat will come. It takes that kind of one-upmanship - the recognition that the odds are stacked in your favor, and they have room to back out.
Is that more what you need? And sorry I sounded gruff at first. It's a point I went through to arrive where I am - just trying to be concise with my experience.