This is a bit of an odd move. Gohara has barely been stretched out to handle a starter's workload this year. Moving him to the BP now means he will need another 3-4 weeks minimum to build up the pitch count to be a starter if/when the team needs him, unless this is a promotion intended to only be a week or so in duration.
I have a hard time agreeing that letting Gohara sit in the BP getting 3-4 innings per week in May is a good development plan for him though. At the end of the season to limit innings? Sure.
I expect to see him moved back to the AAA rotation before he no longer has the endurance to throw 60+ pitches.