How does that not also apply to TFA?
I actually don't think it applies to TFA. In that movie, Finn is willing to do brave and dangerous things right from the beginning (escaping in the TIE). But he never commits an act of bravery for anything other than escaping or protecting Rey. When he leaves Maz's castle, he even committed himself to leaving Rey and the Resistance because she was presumably safe with Han.
Finn was determined to run away because of his fear of the FO. And he didn't stay out of bravery, or to join the fight. He stayed because the FO attacked before he could leave. Then he saw them take Rey. Joining up with the Resistance, and going to Starkiller, was all still to save Rey. That's it. No loftier ambition, and no greater purpose. Just devotion to Rey.
At the end of TFA, Finn stood up to Kylo in the lightsaber duel. Again, that was another brave thing to do; but he only did it because Kylo was trying to kill Rey. Then Finn went into the coma. When TLJ picks up where TFA left off, Finn's motives haven't evolved when he wakes up. He's still the guy who would've been happy to run away, but was willing to put his neck (or spine) on the line for Rey. That's exactly what he was doing at the beginning of TLJ: Ditching the Resistance with the singular focus of being there for Rey.
By the time we see Finn willing to sacrifice himself for the greater good, it's because he actually evolved during TLJ. His bravery manifested for more than just running away or saving Rey. He was now a full-fledged fighter for the Resistance, and any victory (no matter how ultimately insignificant) against the FO was now worth giving up his life for.
So, Finn at the end of TFA = 1.) still a guy willing to run away, 2.) not actually part of the Resistance, and 3.) willing to be brave for his or Rey's safety. At the end of TLJ, however, all cowardice and selfishness are gone. Finn was no longer just driven by safety for either himself or Rey, but rather had become an invested member of a fight against tyranny. Willing to die for a greater cause. Big difference, IMO.
And in the beginning of TLJ he wasn't "wanting to run away as a coward." That was Rose's misconception. Don't be a Rose.
Yeah, I agree with you that Finn wasn't really being a coward when he tried to leave in the escape pod. But, he was driven by selfish motives in his willingness to ditch all the others.
Right from his first line of dialogue in TLJ ("Where's Rey?"), it was made abundantly clear that Finn was still singularly focused on making sure Rey was okay. He wasn't thinking about the Resistance or the fight against the First Order; he was just there for Rey.
Getting to the escape pod wasn't for the purpose of fleeing himself from the battle. He was taking the tracking beacon away from the ship so that Rey wouldn't return to a death trap. That's not cowardice, but it's the same level of nobility (lack thereof) that he had *throughout* TFA. Finn in TFA was always willing to stick his neck out for Rey, but not for any other purpose.
