If one just wants to avoid association with "bad" companies, countries etc. That's really an aesthetic concern, not an ethical one.
I do have some things I prefer not to associate with, but it's not because of any sense of purity, it's an aesthetic preference. For instance, certain filmmakers who have acted in terrible ways. Their actions stick with me and make it difficult to enjoy their films. But again, that's an aesthetic preference. It doesn't compel me to any consistency in the movies I watch and it certainly doesn't constitute a moral argument that I could tell others they must abstain.
Boycott is something different. Boycotting is mostly an attempt to change the incentive structure so that it is in a company's (or I suppose country's) best economic interest to do what you would like. Or else it is part of a wider strategy to get visibility to change the incentive structure so that it is in a politician/party's best interest (retaining or gaining votes) to do what you would like.
But at it's root's boycott is a pragmatic strategy. So for me to decide not to travel to Japan as a boycott, it would need to be part of a well organized, and highly publicized, specifically targeted effort. That effort would need to exert a specific range of economic pressure that could be reasonably predicted to at least possibly tilt the relevant politician's self interest so that whatever they get out of their current policies of police tactics is outweighed by their loss of electability because of the anger at the lost tourism dollars.
Without that structure in place, a moratorium on travel is pretty much an aesthetic gesture. I suppose I don't hold it against anyone who chooses to make that gesture, but I don't have any need to myself.
Funny enough, I'm headed to Japan on Monday for my first trip to Asia. Strange thread timing. Maybe I'll bump into Lionking there.