And that's a fair disagreement. The 120 deg limitation is a TERPS design standard, not a pilot regulation.
However, to go a little bit deeper on this scenario, we have to first pretend we're flying without GPS.
Old-school flying without GPS, you'd not turn inbound until you actually crossed the BLF VOR. Which means that you will cross well through the course centerline as you turn and will go well to the side of the course as you correct back. This is called "outside turn expansion" and is accounted for in Victor airway design - more airspace is evaluated for obstacles on the outside of a turn than on the inside (V-airway only, not applicable for most GPS routes). Although airways are 4 nm either side of centerline, a faster aircraft at cruise speed can easily take more than 4 nm to turn, and the greater the amount of turn, the more space it takes. Airway design is very generous with outside expansion for this reason.
However, that's for airways. While VOR-based initial segment on an approach procedure are also 4 nm either side of centerline, there is no outside turn expansion applied. This is (as far as I can tell) the main reason for the >120 deg turn prohibition. So if you ARE in the OP's scenario, making more than 120 deg of turn and waiting until you cross the VOR to begin that turn, it is "possible" you could go outside the protected area. Now, that's not very likely in typical light GA aircraft but in something in the 200+ kt range it gets pretty close, especially with strong wind from the "wrong" direction.
So, it's something to at least be aware of.
Now, on the flip side, say you're flying this with a modern GPS with turn anticipation. That potentially faces the opposite problem if you choose to just make the 120+ degree turn to the inbound course. Because in that scenario, the tighter the turn, the more it's going to have to lead the turn. At some combination of ground speed and amount of turn, that turn may have to be made so early that it's outside the protected airspace on the INSIDE of the turn. This is one of the reasons for the 90 deg turn limitation on GPS procedures.