That said - unless you have the StewMac kit, it could be a bit of a pain to remove without doing a bit of damage to that fine colour you've got. Hence...
Option #2 and this will get me to the naughty room for sure. Drop of CA glue on the screw head and glue it back on to the rest of the screw. Given it's one of a dozen or so pickguard screws, it's not going to be carrying a lot of weight. You will want to be careful as you don't want to superglue the pickguard on. You will need to be eternally vigilant though that a simple knock doesn't leave you with needing to fix the issue months later without the head to the screw.
Option #3 - cheaper than the StewMac kit - new pickguard with no holes drilled - make sure you don't overlap the hole and you should be right. It looks like there isn't much of the old screw that is sticking out from the body so it looks like it could be done.
Not sure if any of these are what you are looking for. I know #2 & 3 don't actually fix the problem, but I understand that $75 + postage is a lot to fix a single screw in a single guitar. Others may also have similar / better solutions.