I still don't know how Red Hawk works, but Law's move this chapter was simply to "honor" Corazon.
No one was on that track when Robin used giant limbs with her ability. Maybe she just honored Saul.
And Law can do whatever the f he wants in his room. Quote: Smoker.
BB obtained WB's powers somehow from his dead body. And Doffy ended up having Ace' fruit who was coincidently present at the summit war.
And when Smiley Slimey died a random apple turned into a DF. The next arc a Doffy-goon (not Vegapunk, still sad he wasn't shown yet) explained us what happens to an ability if the user dies.
Another case where I am more comfortable to buy that theory is Big Mom:
Carmel had her fruit for a long time. Decades. When Big Mom (probably) ate Carmel, she MAYBE also inherited Carmel's "evilness",
since maybe users also can influence the "demon" of a DF if they run around long enough with that ability.
But you know what? I respectfully can agree with this.
When BigMom (probably) ate Carmel, her demon had no where else to go but to Linlin.
When WB died, maybe BB just used a cloth made of seastone, the demon had no where else to go but to BB.
Law/Corazon's and Luffy/Ace' deaths could have caused some partial thing, where Luffy/Law obtained partial powers from them.