Others with more knowledge will I'm sure have more insight but I feel like this is in the range of "normal" "full sized" for bass bows. As with basses I don't think there is a specific cut off with sizes of bass bows and there is a ,to of variances. It seems that there are two general sizes that people tend to make and use, one being around 22inches in the measurement you gave and the other being about a inch or so less.
I know I for one like bows on the shorter side, but thats just preference. For example my main bow is a little over 21inches from ferule to the back of the head, so I guess the bow you posted maybe a little on the short side but I don't know if it would be considered less than "full sized" Think of how many basses fall in-between the labels of 5/8, 3/4, and 7/8ths. It seems just almost everything with basses haven't even come close to becoming standard, including their bows.