is there a extra penalty for declining part of a mission chain?

my example : declining part 2 of a 5 for portal of war.

because the chain itself does not seem worth it, you kill a bunch of caldari/amaar instead of pirates who give bounties.

but part 1 specifically seems good, wondering if i am allowed to do part 1 but then just not do the rest of them.

ik normally you can decline for free once every 4 hours, but idk if this is a exception maybe.