No I bent the pin out from the programmer. so the 25V is only roots though the chip, for which it is designed. I guess if it is fulty it could fry your programmer, so test on a disposable one first (I have a dead one somewhere). Always lookup the datasheet of the EPROM, they like to move the VPP around. In regards to why the 25V is litraly just between the VPP pin & the GND pin, so there would have to be internal shorts for it to find another way though the chip.
I supose you could add some relay control or something simular so the programmer could root the 25V to the EPROM. Just disable the pin detect or it will error on you. Otherwise the 25V into the EPROM is user controled =-)