As far as if he goes in Dubai (or any country which has no tax on bitcoin), cashes out, develop a business etc, that is ok but when he will move back to his won country he would have to pay his taxes on the amount which he currently holds as per his country law. There is no way you can escape from tax.
It depends on tax policy, again. My country exempts taxes for foreign income if the taxpayer has complied in the country where the income was earned. Assume that Dubai is completely tax free, at this point OP can make good excuses and some technical preparations that the 10 BTC was earned while in Dubai (eg moving 10BTC gradually to another wallet). cmiiw