Everyone knows where celestial dragons live but decided to sit back and whining. Poor Jinny need to crawl back by herself.
Pre-TS zoro has bigger ball than the whole army combined lol
Just a couple of things to mention and counterpoints:
While the CD's live in the Holy Land, it's size has show to be gigantic (at least similar to EL) and there are slaves everywhere. Attacking the base without knowing where she is specifically would just create a hostage (if they just don't kill Ginny outright) even if they had the numbers to face the WG/knights (they didn't). And this is assuming that she is in Marijeoa and not in a island somewhere that a CD destroyed to make a summer home.
At the same time, while a frontal attack is suicidal/stupid, it has been show that a single or a small squad can succeed. Kuma also has show mastery over his fruit and could make a hit and run to rescue Ginny, if he knew her location. Invading without knowing her location would be a bad move because Kuma is not built for sneak missions.
Dragon was a ex-marine and his father was Garp. There were ways for him to learn where she was taken. Like, just begging Garp would do if things got desperate (Garp was not show to be without morals and would help, even if acting as a enemy on the surface and give at least a hint of where she was).
My theory is very simple: Dragon decided that Kuma was too valuable to risk losing saving Ginny and didn't do anything because losing Kuma would be crippling for the young movement. We saw Kuma handling things single handled. Ginny was a small sacrifice for the cause. Later, just the fact that he promised to help Bonnie was enough to have Kuma on call 24/7. So he sit on his ass about Ginny and Bonnie (notice that Kuma is the one to find a good doctor and not Dragon), and use Kuma as a weapon for his cause. Notice that when someone he actually cared about (Kuma) was captured, he gave the orders fast. Kuma was a slave for a couple of months max before he was freed.
TL/DR: Dragon didn't give a rat ass about Ginny. He just wanted to use Kuma for his cause.