That doesn’t take the soldermask registration variation into account, which depends on the fab and is not expressed as a percentage but as an absolute value.
Their blog talks about 3 mil minimum clearance, so I’d say that they are able to place it +/- 3 mil, while still being able to guarantee that your pads are 100% free.
Economic fabs (esp. Chinese) will give you 4 mil (0.1 mm), while the better ones are able to guarantee 2 mil (0.05 mm).
0.707 x 0.2 mm is ~0.142 mm, not 0.154 mm
If you then take the 3 mil (=0.077 mm) registration tolerance into account you wind up at a soldermask clearance of 0.065 mm that you should not exceed, if you want to make 100% sure that no copper track is exposed.
PS:
I use 0.05 mm soldermask clearance, 0.1 mm soldermask minimum width and 0.2 mm track clearance for these kind of boards.