The exploit code isn't available for anything beyond 4.01 I think so no you can't do anything besides keep from updating in hopes that a hack for your firmware is released. Downgrading machines is relatively pointless as the only way a "downgrade" is possible is using an exploit with the same permissions as the exploit you would be downgrading to use. Further more iirc the PS4 uses efuses to ensure that the nand can't be downgraded without bricking..... (basically the boot loader will expect a certain number of fuses blown based on the software version. Anything different and it causes a kernel panic resulting in a haunted boot.