I don't find this to be a strange argument, not in the least.
Mullins was our best offensive player when he went down with his injury, he was having a fantastic season. One could even argue that Mullins is an offensive force. No one can say the same about Mountcastle...as a matter of fact, Mountcastle was having his worst season in the majors. I've pointed it out before a few times (others have, too) but he's been on a decline year after year since he arrived in the majors. Slash lines, OPS+, all the stats point to a guy in decline. I don't want to hear how unlucky he's been, he's not unlucky when he's swinging and missing at sliders out of the zone and rarely taking a BB.
So for Mullins to only have one hit in his rehab assignment is a blip on the radar. It shouldn't even be a blip, it shouldn't even register with anyone, anywhere. What mattered the most for Mullins on his rehab assignment was that he could run without pain and that he could do all the things he could typically do on a ballfield without aggravating anything. All that anyone had to care about in regards to Mullins' rehab effort was that he was comfortable on the field.
Mountcastle shares those concerns, too. He needs to recover from vertigo.
But he also was having a terrible season before he was sidelined and his 12 at bats in Norfolk are a continuation of that. In a season when a few people on here were calling for him to be optioned to Norfolk in the first place, it makes sense to be a bit more critical of him.
You'd like to see him tear up AAA pitching. Yes, I know it's only 12 at bats and that's a small sample size but, IIRC, he's striking out at the same clip down there as he was up here.
I hate to view it this way because it's a cold way of looking at things, but Mountcastle getting sidelined with vertigo might be a blessing in disguise for the Orioles AND for Mountcastle. For the Orioles, he's not on the roster and O'Hearn continues to rake in his place. For Mountcastle, it's a chance to do whatever he needs to do to get back to being a capable hitter, maybe even learning a little bit of plate discipline if that's possible for him.