It's hard to say if it's a bad call on your doctors part or an over reaction of the other doctor, since medicine isn't an exact science.
Doctors opinions differ greatly. I always refer to webmd.com for up to date info. I breastfed while pregnant with my second son and my doctor told my that I must wean immediatly and that I couldn't VBAC and wouldn't be able to find a doctor that would.
After reading on webmd.com and askdrsears.com that breastfeeding while pregnant is safe for most women (it's rare to get really strong contarctions from breastfeeding) and that vbac was my best option, I switched doctors.
I told my new Dr that I was breastfeeding and she wasn't thrilled, but she didn't panic like my first doctor. She also said that I could try a VBAC.
If you feel uneasy with him, I say switch. You don't want to be in the middle of labor doubting your doctors desicions.