This is absolutely correct. GPS Panel is designed to show real and the actual GPS position and if it is not available it shows default position (hard coded because it needs to show something). Should you consider any other approach do not hesitate to suggest it. It was just my assumption but I would be more than happy to do it the way you want.
To change this behavior you need to change gpspanel.py file, which I do not recommend because all the changes will be overwritten by future updates. So it is better I change it for all the users.
Changing astropanel.conf does nothing to gpspanel. It just works with Astro Panel, which calculates bodies positions for a specific location (which can come from GPS or static config).
BTW. I agree it is kind of a mess but I haven't came up with a good solution. As for now there are separate locations for:
1. Astro Panel (GPS or astropanel.conf file or Weather Plugin location)
2. GPS Panel (only real GPS receiver)
3. KStars (GPS or static configuration of KStars location)
Any ideas how to combine these? Bear in mind that before first start of Kstars it's configuration defaults to London, before connecting GPS receiver GPS Panel defaults to Warsaw, before setting up astropanel.conf Astro Panel defaults to GPS or Weather Plugin