I mean, if they actually did move their HQ (ie majority of costs, execs, etc) to Singapore, then sure. And that'd be totally fair.

What maybe doesn't seem fair (haven't thought about it deeply enough to say for sure) is pretending your HQ is where you really just have a satellite while the core of your IP creation, expenses, exec decision making etc is in the US. It's like you're getting the benefits of being in the US (whatever you think they are), but not paying the full price for those benefits.

What I hate about rules like this is that it basically forces you to follow them. You have a fiduciary duty to shareholders as an officer and/or director, and so you have hard time justifying not using a technique like this.

That's a common strategy, but not quite so simple to pull off. One approach is through M&A: https://en.m.wikipedia.org/wiki/Tax_inversion

Twitter made this same threat with San Francisco when it extorted us for corporate welfare. In reality we should have a tax system which rewards job creation and creates very stiff penalties for trying to sneak out of paying for the infrastructure which makes their profits possible.

That would be amusing; would Eduardo meet them at the airport?