I don't think I fully understand your question. Do you mean is it to stop a Pokemon such as Zekrom with Terravolt Bolt Striking? Because if so, I think it only passes through abilities, not typing. So it would hit a Pokemon with Bolt Strike but not ground types.
TBH I have considered this before and see little use or reason for it having Lightningrod. Why would a ground Pokemon need to draw in electric attacks. However I think Gamefreaks intention was for it to be used in double battles in conjunction with a Pokemon weak to electric.
A lightning rod is typically a rod placed high in the sky to draw in electricity. Rhydon shares this ability with Seaking who also has a horn that points to the sky, likely to draw in the electricity. This is a possible reason for why it has the ability, despite it being pretty redundant.