Having an older supervisor who is not an associate professor may not be career suicide, but it raises important considerations. Key factors include the supervisor's experience, research funding, and their potential to remain at the institution throughout your PhD. It's advisable to discuss their connections and expectations early on, as well as the composition of your supervisory committee. The tenure situation varies by institution, and working with a rising star could benefit your career if they have strong recognition in the field. Ultimately, the decision should be based on a thorough evaluation of the supervisor's qualifications and support system.