Didn't you say the 2017 payment was $30K? That is part of the itemized deduction. So if you had (let's say) $12K in other itemized deductions and would have used the standard, you would now have $42K in itemized deductions. So you get some benefit, just not all of it.
I can't really advise you on the meaning of "unrestricted". It would not be unheard of for you to take the most favorable tax position you can, and worry about your audit later, since only around 1% of taxpayers are audited. If the IRS reassessed the tax as an itemized deduction, and you decided not to fight in court, you would owe the additional tax plus about 1% per month in interest and late fees.
It would be up to you to decide if that is a risk you are comfortable taking.
