I don't think it's a reach at all. The temperaments are a fundamental aspect of typing in my opinion and there's a strong difference between NF and SP.
From Keirsey.com:
As Abstract Cooperators, Idealists (NF) speak mostly of what they hope for and imagine might be possible for people, and they want to act in good conscience, always trying to reach their goals without compromising their personal code of ethics.
As Concrete Utilitarians, Artisans (SP) speak mostly about what they see right in front of them, about what they can get their hands on, and they will do whatever works, whatever gives them a quick, effective payoff, even if they have to bend the rules.
NF musicians:
Bob Dylan
Neil Young
Roger Waters
Joni Mitchell
Sixto Rodriguez
Ben Harper
Bono
Peter Gabriel
SP musicians:
David Lee Roth
Axl Rose
Jimi Hendrix
David Bowie
Beyonce
Britney Spears
Justin Beiber
Madonna
And an ESFJ making a Christian Rap Album is definitely different. ESFJs are not wired to change the world. INFPs are. Quite a big difference if you ask me.
As Concrete Cooperators, Guardians (SJ) speak mostly of their duties and responsibilities, of what they can keep an eye on and take good care of, and they're careful to obey the laws, follow the rules, and respect the rights of others.