The article mentions this already (that meteorites on earth have been found with amino acids). The important difference here is the in the Murchison case, it was already exposed to Earth's atmosphere and environment, so you couldn't be sure where the amino acids came from.
Yes, but the fact that thirty three of these Murchison amino acids are 'unknown in natural materials other than carbonaceous chondrites' gives pause for thought.
That meteor is either proof of pre-Earth life, since those amino acids aren’t known to exist in rock otherwise or proof that the relevant amino acids can be created by an abiotic process. If you don’t want to believe the meteor has been contaminated since it hit the Earth.
Apparently it's thought that meteorites hitting the ground freeze water around them after a bit. They get heated up, but it's pretty short, so the bulk of it is "space temperature" only the surface is heating. And a lot of the stuff that heats up is ablated. (depending on size)
Unless the stuff is on the surface of the meteorite it's probably fine.
