I don't see a problem doing any kind of a drain, but I'm not there to see what the plumber may be seeing. To plumb it up, you'd either have to get underneath, or tear the subflooring off unless the distance is short enough to reach.
One complication may be which way the joists run and where you want to put the drain. If the linear drain would cross over multiple joists rather than sit between them, if you try to recess it into the floor rather than having your mudbed thick enough to keep the body above, that could be a major problem.
Maybe a sketch of the area showing where the shower is supposed to be and the joist layout may make it clearer. You can attach a file when posting...use the 'Upload a File' option and upload it from your computer.
A linear drain is often installed at the back of the shower along one wall. But, it can also be installed in the middle of the shower with two sloped sections, rather than one, which gives a bit more flexibility.