Well yeah, if anything it's even worse. There are mechanics that make it virtually impossible to wage war at great distances in BM. Tom has repeatedly said that this has been done on purpose, and various suggestions to make it easier to wage war on the other side of the island (cash bonds in allied cities, recruit anywhere in your realm) have been shot down more than once based on this exact justification. Carving out a forward base a long way from home to make it possible to wage war at a long distance seems exactly like the sort of meta-game shenanigan that the strategic capital move rule is aimed at preventing in the first place.
It sounds like, from what you're saying, it would be
worse if they didn't secede the city, because then they'd all be able to cash bonds there to pay their men and repair equipment. If they
did secede, only those who joined the new realm would be able to cash bonds, and though they would be able to recruit, the only troops they'd have available would be those in the city and whatever small number of regions they had been able to conquer around the city.
Personally, I think this type of play, enabled by sea travel, is different enough than what has gone before that we can't entirely apply the existing rules to it.
Finally, I would note that based on some dev discussion a while back, Tom may be softening slightly on the "no long-distance war" rule, at least under limited circumstances. I just haven't had time to implement the changes he has approved along that line yet.
