Because some will have fixed above the current price cap but less than the October price cap. Freezing the prices where they are will mean those people are paying more than others.
Because people who have locked into a fix in the last 6 months might have locked into 4-5k a year bills out of fear of bills continuing to rise over the next 12-24 months. They most likely have exit fees of £150 per fuel to get out of those deals as well. They may not have an extra £300 to get out of those deals and if svr is capped at £1900 when ofgem is forecasting costs to be much higher, unlikely to be anyone recruiting openly on the pride cap.
By helping one group you disadvantage another, although it is likely to be a smaller group.
I don't think I agree that this "disadvantages" them. But I may not understand it fully. Those people will pay their fixed rate irrespective right? Whether or not the cap goes up for others?
I understand you're saying they may not have chosen to go on a fixed rate if they had prior knowledge that the cap definitely wouldn't be increased. But that's not them being disadvantaged. Surely that's just what a fixed rate is. You're gambling that costs may go up and the energy companies are gambling that it won't?