Firefox is open-source and can be legally modified. Opera isn't.

True but not relevant. This isn't a privacy thing, its just purely about accessing pirate bay and other blocked sites. So open source and so on is irrelevant in that goal.

Edit: Quote added. "“This browser is just to circumvent censorship, to remove limits on accessing sites governments don’t want you to know about,” The Pirate Bay notes."

Does the Opera license allow to distribute modified versions setup to automatically use Tor for .onion URLs, without getting special permissions from Opera Software?

In addition: Why Opera? I don't see any significant advantages over Firefox. There are probably more users who are familiar with Firefox than with Opera.

Also, being open source, one can evaluate the source code and check the "secure browser" isn't leaking secrets.

Maybe they just wanted to use Firefox.

Why not explain why they should use Opera?

Because some people don't use un-free software.

And that's why this ‘Pirate Browser’ only runs on Windows...

I know you are poking fun, but it is legitimate to start working on something that is opensource and free on an unfree OS to one day offer the minority that are on a free OS the option.

Looks like they're basing it on previous work done by the Tor Browser Bundle (which actually does have Mac and Linux clients).

Because opera is just reskinned chrome.

How so? There's more to a browser than a rendering engine you know.

And until recently Chrome was just a re-skinned Safari?

Right.

Safari is just a re-skinned Konqueror, anyway.

And that stops UK users accessing TPB how?