The old ones are full of oil. They should, however compress a bit when you lean on them, otherwise they have turned into solid lifters which is not what you want. You can pull them apart and clean them up, they are probably full of sludge. Your mate is right.
The new one will fill up and "pump up" once it gets oil pressure, but they should never be hard.
Reinstall each lifter in the position they came out of or they need to be reground or replaced.... each one is "mated" to the lobe it's spent time following.
I recommend replacing the lot.