Pre-2013 Disabled discretionary Trust

In a Pre-2013 S89 Disabled Discretionary Trust (where half a fund of £120k has to be used for the Principal Beneficiary during their lifetime) would a payment to other nominated beneficiaries of a total less than half the fund breach the rule? If so, what is the effect? It would seem that the S89 IHT protection would be lost, but does it then simply remain as a discretionary trust, but without the IHT protection of S89? As can be seen from the value of the fund, IHT protection is not really needed.