As Simon says, the withdrawals from a DGT are capital, not income, and so would not be treated as gifts out of the settlor’s income.
A concern may be that the settlor never really intended to receive the regular payments to which they are entitled. In which case, HMRC might assert the creation of the scheme is a sham (as it was never intended to operate in the manner set out on paper), or that there are associated transactions, as the subsequent withdrawals are retained in the trust.
My view is that the withdrawals due to the settlor should be paid over to them soonest, and future payments paid over as they are received.
Once in the settlor’s hands, if they have an annual income surplus (ignoring the payments from the DGT) then they could establish a regular pattern of gifts out of income in order to reduce the build-up of their estate. Whilst a little more fiddly, it has more chance of passing HMRC scrutiny.