beinghuman
I suspect perhaps you are being confused by terms and definitions.
Regulated Take off Weight is the maximum weight at which you can perform a particular take-off. It is the lesser of the calculated performance limited weight and the aircraft's certificated MTOW. In the case you quote, the MTOW becomes the RTOW, i.e. 73500kgs.
The performance limited weight is a "maximum" of course but in terms of definitions it is not MTOW.
I have to join the ranks of those raising their eyebrows at the concept of on-the-day flexing of MTOWs. Could be it be that denti's company is, shall we say, exploiting a loophole ?