Price fixing is legal as long as your are doing it in the open. In the UK it is called "price match" and eg. if supermarket says they keep prices matched to their competitor. No regulator raises an eyebrow. So here Samsung and SK Hynix could say they price match to Micron and they are in the clear.
No, the key term is "collusion", which could be done in the open or not. If a competitor told you they were unilaterally raising prices in secret, that would still be legal. Where you get into trouble is if you are cooperating to set prices. And no, this is all determined by a judge so cute workarounds like "I'm telling my competitors that I'm raising prices then gauging his body language" won't work.