Yes. He's less electable, and not just in a primary sense. He's dull, but at the same time, he has his brothers unintelligent appearance. He reeks of elitism. He's not going to rile up GOP base voters and he's not going to get anyone from across the aisle to vote for him because he's not convincing. The GOP thinking Jeb Bush is the guy who is going to lead their party is why the party is in such dissary in spite of huge midterm electoral victories. The GOP can definitely do worse than Jeb Bush, but they can also do better.
The idea that conservatives are less electable than moderates is basically incorrect. Jeb's less electable than the pundits think.