The important words in that passage you quoted is “paid to you”. If the rollover is paid directly to the brokerage receiving it then no withholding is mandated.
You would hope, I agree, but for some reason, even for Roth conversions between accounts within a brokerage, some brokerages seem to interpret that as being different to an IRA rollover in terms of withholding.
I have done IRA rollovers too, while living in the UK, in the way you describe and was never subject to withholding. In topic 413, the IRS include Roths in the concept of a rollover - and they say that rollovers are tax free, except for a rollover to a Roth (a conversion). That is possibly the difference causing the problem, an IRA to IRA rollover is not taxable, where a Roth conversion can be, so the withholding rules are different. Or some brokerages have taken a conservative view and decided a conversion is the same as a distribution, regardless of how it is done. And distributions are subject to withholding if you live outside the US. That's not how I interpret the IRS guidance on retirement plan rollovers, but that doesn't make any difference of course!
I should add, my last post was not so much about whether withholding was warranted, but if it is unavoidable, I can at least make up the funds in the Roth and avoid a penalty.