It's certainly a legit kill, but it still remains seal clubbing: A completely one sided engagement against a palpably weak foe.
I see your reasoning, but you actively placed yourself in a position to be attacked. To me, seal-clubbing is when over-powered ships actively pick on far weaker ships in SC and interdict them to destroy them without any provocation.
E.g. A Deadly pilot in a fully engineered FDL cruising the starter systems attacking Harmless Sidewinders is a seal-clubbing no-talent Richard.
That same FDL attacking the same sidewinder in an active Combat zone is just as one-sided, but the sidewinder went there of his own free will to fight other ships. The FDL may be accused of being un-sporting etc. But as they are both there specifically to attack ships on the opposing team it is no longer seal-clubbing. It just means the sidewinder is extremely optimistic about his chances.