I don't think taking a photo will have any actionable follow-up—I have no way of following up to see if someone reports to see anyone has reported a stolen bike in the area—but might make a thief decide to go find a different target, while not being a major issue if you're the actual owner.
As a healthy, medium-large guy who's okay at de-escalation, I live in the assumption that no one will try to hurt me for interfering. I'll probably learn better one day.
Of course, it's quite possible that the Average Bike Thief in Amsterdam is a well-organized criminal-for-hire kind of person, doing surgical strikes against the most valuable bikes and so on (as is often the case with car theft, afaik). Then perhaps an angle grinder is just standard Day 1 equipment.
As ever, impossible to stop a determined thief, but starting to get "good enough".