I wish I knew enough about the technical aspects of this issue to know who’s right. The modified military rocket approach seems to make sense - it’s readily available and would build on proven designs. But I just don’t know enough about the safety factors and other considerations to really say for sure.
The Russians and the Chinese use military rockets to launch satellites and manned craft.During the Soviet period, most Russian military payloads reaching the orbit would be identified only as Kosmos satellites with particular numbers. Any civilian satellites, whose purpose the government would not want to explain, would also receive Kosmos names. To this day, the Russians use military rockets.
It makes good sense .... the biggest problem is the difference between satellite-rated and man-rated. You need to "add 9s" to the reliability numbers once you put people on-board -- which means a lot more people and a lot more safeguards, and that adds a lot to the cost.
Still, they're part of an existing product line, and if you could create some sort of re-usable command module that would be good.
The safety issues are the concern. Required reliability for man rated launch is much more than for non-human payloads. That reliability come in the form of expensive redundancy, more reliable and expensive parts, and much more testing and evaluation.