Exactly, and surrounding a stranger plot with your own plot does not look like a good intention. Especially when you are building a road. Why does the road have to be on every side of his plot? Why can’t it be just on one side? 
Normally I wouldn’t write anything about what you propose, but CoC explicitly say it’s griefing. I really am against any CoC that tells you what you should not do, when it could be enforced on the game mechanics level. I understand that no swearing, no racist text on signs etc. has it’s place in CoC, but something like “Plotting around another players base, with intent to stop them expanding” is one side clear, on the second ridiculous.
If I settle in town, plot 4 plots, and after a week you build a road around my plots, and other people start building other things beside that road… with current CoC it’s considered griefing, You, with your road, limited my ability to expand But isn’t it how cities are supposed to be build? Madness!