They don't have to release the info when he wants it, assuming they have it in the first place. Remember, he's not asking for the release of photos they already have, he's demanding they take a 100 new high res closeup images following his instructions, and 24 microscopic images, also as per his instructions.
The Freedom of Information Act has nothing to do with his demands, it only covers information the government has, not stuff that hasn't even been done.
He's not a NASA administrator, supervisor, project lead, project member, or any other kind of NASA employee of any kind. He has the same authority to demand these things as any other American citizen, zero.
That rock is interesting and unique, but then again, so is every other rock they check out. Since it has wildly different mineral levels than most of the others, it would be very interesting, at least for geologists & mineralogists, to have a more detailed examination of that rock, but whether or not it will happen depends on the limited resources they have available, and if it shoots to the top of the priority list. There are a lot of things there that the scientists on the team are jonesing to check out.
Is it life? Um, no. That's not an absolute, but the probability of that rock being a life form is less than you winning the lottery and getting hit by lightning.
Does Mars have life? Maybe. Of course there's also the chance that Mars had life, but it's all extinct now. Sure, a probe might find it, but they are not well equipped to find or analyse that kind of thing. At this current time, it would be a task optimally performed by a human on Mars with appropriate tools. Skilled humans are very effective, capable of dealing with unknown situations, and not crippled by a 30 minutes time delay with every instruction. Actual time varies depending on orbital positions of both Mars and Earth. This is also assuming 2 way communication, sending instruction, receiving reply that instruction was received and possibly resultant data.