can you empower the same unit you disempower with profiteer

Yes — you can empower the same unit you disempower with Profiteer.

Profiteer's disempower is the cost, paid before the empower effect resolves. Disempowering removes the Empowered status (Rule 442.1), so by the time you choose the empower target, that unit is no longer empowered and is a perfectly valid target. The only restriction on empowering is that you can't empower something already Empowered (Rule 441.1.b–c) — disempowering first clears that.

Note the empower half of Profiteer doesn't even say "you control," so it isn't restricted to the unit you disempowered — the same unit just happens to qualify.