This does actually make sense with the timeline he was given after undergoing back surgery in mid-June. It's still unlikely Gronk sees the field in week 1.
According to the Boston Herald though, Gronk could come back as early as Week 2.
"There are whispers at Gillette Stadium that Gronkowski could play as early as the home opener in Week 2 against the Jets," writes Jeff Howe. "Though that still seems a bit optimistic, it hasn't been ruled out, which isn't a bad thing."
I would be opposed to Gronkowski returning that soon. I would rather him fully recover from his surgeries before putting himself at risk again. The play of the Patriots offense without him will likely dictate which direction the team goes.