yitayningwut
I can’t go into everything at length here, but just briefly:
1.
“The poskim say as a davar pashut that a printing press is kesivah mid’oraisa.”
I highly doubt it. If that were the case, our Sifrei Torah would be written using a printing press. (leshmah and maaseh ksivah have the same parameters b’pashtus. If it is a maaseh ksivah, which means it is like writing by hand with a quill, then it is enough for leshmah as well.)
2.
I acknowledged that it is derabanan. But it would still help out when being metztaraf other reasons that could render it a sefak (machlokos rishonim usually has the din of a safek), or a shvus deshvus.
And here you actually “helped out” the tzad for heter, by bringing up another issue: it is ksav shaeno miskayam al gabay davar sheino miskayam. You allude that this is a mechlokos, which gives more room for a tziruf leheter with other issues.
3. I fail to see the similarity. Ksav sheino miskayam is full %100 ksav, only it will be erased. Ksav made up of many little dots, is, according to some opinions, not ksav at all
(the practical application is soda cap dates and numbers. I am not saying that you should take on this heter personnaly, but when we are deciding whether or not these people are not considered jewish for many things, and someone even brought up yayin nesech, I think that this should definitely be taken into consideration.)
4. I believe that it is the shita of Rishonim that one is only chayav for ksav ashuris. See the Chayei Adam shabbos 37:5 (“rov” poskim etc.)
5.
The sugya of grama is too wide and deep to go into at length here.
If i am correct that there are rishonim who hold that you need a “maaseh ksivah” for hilchos shabbos (notably the Ran is of the opinion that maaseh ksivah is only a din in Hilchos sefer torah, but i think that this is a chiddush of the Ran that not everyone agrees with), then you have a pretty clear heter already: it is for sure not more than a derabonon because it is ano miskayaim, and these rishonim would make it a safek derabonon between them and the Ran.
That is just one way that these reasons can be used in tandem to find a heter, using the first sevara.
(btw, i am not sure that i used the word “metztaraf” here the way it is used by the more recent poskim. I only meant that by using two sevaros together, there might be a heter to be found, in some way…)
Anyway it was an enjoyable discussion 🙂
Due to time issues, i may or may not be able to respond, if you respond again to this.