why should they not have the right to ask you for those foreign tax authority details? It is up to you if you give them, but if you not give them, they have the right to revoke your account.
That seems normal to me, 30 days can be a bit short for a holiday, but over 60 days or even 90 days and then again within a month has nothing to do with tourism, so it is a correct decision of the immigration officer.