At the equal time point, the time of flight to the destination and the divert field is the same. Forecast winds are already taken into account. If one assumes the flight will be at the same altitude, the fuel burn will also be the same.
The "same altitude" assumption is valid operationally, because equal time points are usually figured for engine-out and/or loss-of-pressurization situations. In either case, the aircraft will be likely flying at an altitude governed by the situation, not by ATC (yes, an emergency might be delcared to get that altitude).
The "same fuel burn" assumption is also valid in the engine-out case, because the likely configuration is either long-range cruise speed or max continuous thrust on the remaining engines (or both). It is unlikely a significant headwind or tailwind correction will be made.