How to handle a possibly biased editor? Suppose a journal editor rejects a manuscript with only one reviewer’s feedback, but the few comments the reviewer and editor made were almost entirely minor comments (e.g. “use these units for this figure axis”, or “this section heading is misleading”).

Suppose one author shows the feedback to several trusted faculty members at their institution who are familiar with the work, and they say it looks like the reviewer, the editor, or both are feeling threatened by the paper and may be trying to make sure it doesn’t get published quickly, if at all. 

A similar question has been asked here (How to deal with an unethical editor?), except that question was asking about an editor who was making up comments for a reviewer. Suppose the authors have no reason to believe that the editor is making up comments for a reviewer, as in that question, but do have reason to think the editor may have too quickly dismissed the paper (after only one reviewer’s comments rather than waiting for the second reviewer, and based on very minor details that should have prompted minor revision). Suppose, for the sake of the question, that the editor and perhaps the first reviewer indeed appear to be acting in bad faith, which of course would be difficult, if not impossible, to prove. In other words, what if several experienced researchers suspected real foul play, rather than a grad student feeling miffed about a rejection? 

What options are available to the authors in such a situation? (This is not a “what should I do?” question.)

Background

This question is most useful to the community when it is asked generally, so I originally omitted details. Several have asked, so I am including vague details here, but my question is not about my colleague's situation — it's intended to be general. 

I read the feedback. In my colleague's case, the editor rejected the paper based on the feedback from a single reviewer and their own reading of the manuscript — without waiting for the feedback from the second reviewer. Most of the comments were easily addressed (add a sentence here, change units on this figure, rephrase this confusing sentence there, etc.). A comment about some inconsistency in their approach seemed legitimate, and a section title was confusing. The first author, a grad student, sent the feedback to me and the faculty they talked with to see what we thought. There was absolutely nothing about the feedback that indicated it should have been rejected rather than sent back for revision. I'm also a grad student, so I do think much of my own opinion, plus it's not my field. Instead, I trust that the senior faculty who reviewed the feedback and called it highly unusual know what they are talking about. The editor was in a different (tangentially-related) field than that of the paper.
Probably not what you want to hear, but... There's the option of submitting it somewhere else?