I would be surprised... I see nothing 'spin..' about 'Silas Marner' and wonder if there's some mistake and the reference should be about 'Sir Walter Scott' rose.
Oh ok .. I don't have that book but I'm now wondering if he has got it muddled up with 'The Country Parson' which is very much a spin hybrid as they have always stated, and was released at the same time as Silas Marner.
I guess this is the most likely scenario. As you said, Silas doesn't look like a spinosissima hybrid at all, so probably even if there is actually some spino "blood" in it, it is so washed out not to have any influence from a horticultural point of view