I'm not sure how many takers that would get, given all the disadvantages.
- without territory, you'd be hit with a Very High Beyond Frontline Penalty every time
- if it was literal about not holding any space, you'd also not be able to use any Undermining method which required either returning to a friendly system or bringing things in from one [1]; even if you got a single "rebel HQ" system somewhere but no ability to expand you'd be looking at much longer round trips.
- if it was really literal you also wouldn't be able to buy the unlocked modules since you wouldn't have any Stronghold Carriers.
- for the purpose of obtaining rank bonuses, Undermining is generally quite a bit slower and more difficult than Reinforcing even before your merit rate gets halved by BFP and SSP.
The only advantage over just picking a suitable nearby power and using that as a flag of convenience is that you wouldn't need to switch powers for your next target, but that would be traded off against getting merits at about a third of the normal rate.
I wouldn't object to Frontier adding the option for dedicated RPers, but for the "quite a bit smaller than Torval" likely uptake there are probably higher priorities for them even just in Powerplay.
[1] So you'd be limited to:
- Malware uploads
- Crimes
- Mining
- Market Flood
- Support Missions
- Data Links
- Power Kills
- Holoscreen Hacks
which takes out a lot of the more effective undermining options
