Re: "the country has an advantageous business and digital tax environment"
"It requires that both Ireland and NI are in the EU, or if not then at the very least in the single market and customs union."
Why? That is the same as saying it requires both Ireland and Ni to be in the UK. Simply it comes down to NI is in the UK and Ireland is in the EU. If the UK leaves the EU (which is our sovereign right) then either Ireland in its entirety stops crying about the GFA or a trade deal for Ireland is negotiated. And it can be done. Right now they have different regimes resulting in smuggling etc but its considered ok. When we leave the same will continue but is suddenly bad?
"As much as some Leavers think it would be easy if Ireland just did what it was told, it's not going to, it's its own country and there's no particular need for it to make compromises to placate another country's folly. That would be an attack on its sovereignty and all that."
Are you claiming NI is not in the UK? The UK voted leave. However that entire argument very validly supports the UK leaving the EU.