I've seen some statements online questioning whether or not you are qualified to be a witness.

It's a fair question. I believe Jeff when he says he's a major fan of Steemit and will definitely help promote it. However the primary responsibility of witnesses is technical in nature, so any scrutiny of Jeff's plans needs to evaluate his partner, @instructor2121.

The tech specs of his witness hardware published here look good, more than adequate for quite some time to come. I am still curious why Jeff believes having a witness will help him or Steemit. He will be the biggest help in the marketing of Steemit, not on technical matters.

One thing I have no doubt about and that's Jeff's principles. We need people like him to help promote the platform, but I think it's far more lucrative for him to raise any funds he might need via content creation and curation. It's just not clear to me why he wants to have a witness.