It is absolutely fine, in my opinion, to jump in a standing martingale so long as it is properly adjusted. The horse does not need to fling it's head up or out to jump correctly, and a standing martingale provides plenty of leeway for the horse to move his head down and forwards to bascule correctly.
In America they are a fairly standard piece of kit in the hunter/jumper rings, and in this country they are still commonly seen in the hunting field, or on BSJA jumpers.
I think they are a much maligned bit of kit - they are often really suitable for horses with very light or over-sensitive mouths as they only act upon the nose and not upon the bit in the way a running martingale will.