why not? Our friends take from national skater - they love their coach. The downside is that the coach is not available during their events at regionals and nationals, but they are mostly ISI skaters, not nationally ranked themselves and different competition schedules (ISI vs USFS).
I think it can be great to take lessons from a coach who still competes. First of all, the coach is more likely to be aware of current judging standards and rules, and second, the coach still skates well enough to demonstrate everything he/she is teaching. Just make sure you have a backup coach who can work with you when your main coach has to travel for his/her own competitions.
If your personality fits well with them, they teach in a style that you learn best in, and they have all their credentials, I don't see why not.
You would need to have an agreed backup plan for when the coach goes away to compete, however.
A coach who is still currently competing is (or SHOULD) have a better grasp of current rules for levels, spins, steps and jumps, if you wish to compete.