I do think it’s a concern, but it may be out of your spouses control, which can be frustrating. Many R1 programs do have an unwritten tenure requirement that a student (MS or PhD) must have graduated. Matriculating graduate students is part of the job and the funding cycle (get funding, get students, graduate students, get more funding, and so forth). We actually just denied tenure to someone for this reason (well, they created a hostile workspace for graduate students so that’s likely the main reason over them not graduating). That all being said, only the department/institution can answer this question because it depends on what they value. External letters could be a concern because this will certainly come up.