Maybe the doctor doesn’t really understand what the exercises are. The point of PE is to force blood into the penis to make it engorge beyond its normal capacity with the hopes that the strain on the tissues that comprise the penis will go through cellular expansion, or like when we work our biceps, the strain on the muscle makes the muscle cells need to duplicate to deal with the strain next time. If there is no blood flow at all then yes there is the risk of clotting, but I think there’d be penile damage and potential necrotic tissue problems along with any clots.
Sounds like the doctor doesn’t really understand blood flow to me
Starting length, Spring 2003: bpel 6 3/8", bpfsl ~6 1/2", flaccid ~3-4" (never measured flaccid stretched or hanging flaccid; starting girth was probably ~5"-5 1/4")
Summer 2004: bpel 7 7/8", bpfsl 8 1/8", flaccid ~4", erect girth 5.3"
Spring 2018: bpel 7 1/4", bpfsl 7 5/8", erect girth 5 1/8"; Spring 2020: bpel 7 3/4", bpfsl 8", erect girth 5 3/8". Current - August 2023: bpel 7 3/4", bpfsl 8", erect girth mid shaft 5 1/4" (5 1/2" at base)