Lifnei Iveir - Bad Advice or Causing an Aveirah 2

In this post we discussed the issue of how could one transgress lifnei iveir on a d'orayssah level if he only advises someone to do an issur d'rabbanan. We suggested that perhaps the issur of lifnei iveir encompasses two aspects; first, giving bad advice and second, leading someone to do an aveirah. According to this approach, even suggesting that one transgress a d'rabbanan is bad advice and an issur of lifnei iveir mid'orayssah. The Achiezer (3:65:9) makes this distinction and adds that the two categories of lifnei iveir are in fact very different. When one gives bad advice it is only lifnei iveir if the one being advised is not aware the advice is bad. This is not so when one enables someone else to do an aveirah. In such a case, even if the person being enabled is aware of the aveirah, the enabler still transgresses lifnei iveir.

There is another approach to explain the machlokes rishonim by lifnei iveir. The Ramban in Shoresh Rishon of Minyan HaMitzvos takes issue with the fact that the Rambam ties every d'rabbanan to the d'orayssah lav of lo sassur. He argues that d'rabbanans, by defintion, cannot actually contain d'orayssah elements to them, as the Rambam seems to imply. It may well be that the Rambam holds that although d'rabbanans are obviously not d'orayssah, still they are considered cheftzai torah on a d'orayssah level. R' Soloveitchik gave a mashal for this using a case of someone who learned Meseches Megillah (a mesechta with only d'rabbanan dinim) all day. Would anyone suggest this is not talmud torah on a d'orayssa level? Would anyone say not to make Birchas HaTorah on such learning? Obviously, the dinei d'rabbanan are recognized as cheftzai torah, even on the d'orayssah level.

The same idea might apply here. Some Rishonim (see Tosafos Avodah Zarah 22a) understand, like the Rambam, that even if one advises someone to transgress a d'rabbanan, that issur is still "recognized" by the torah, and the enabler transgresses lifnei iveir on a d'orayssa level. The Ramban (See Chidushei Ramban Avodah Zarah 22a) says that the issur d'rabbanan is not recognized at all as issur on the d'orayssa plane, and therefore there is no lifnei iveir on that level.

It is interesting to note that a similar machlokes is found in Makkos 2a. The mishnah talks about kaasher zammam by a case where eidim zommemin say someone is a ben chalutzah. The Ramban asks, isn't ben chalutzah only d'rabbanan? How can it be kaasher zammam mid'orayssah? The Rambam in bringing the case as stated seemingly has no such problem. Again, the issue might be whether the eidus on the d'rabbanan plane is recognized at the Torah level.