Dear Ujm, That is a great reason except for the minor details…
UJM’s reason happens to be brought down here:
https://hebrewbooks.org/pdfpager.aspx?req=2604&st=&pgnum=95&hilite=
Not sure who this is or how reliable he is, but just putting a source out there.
this is well before the advent of seforim
In the source it says that they were learning בעל פה.
the Yivanim weren’t searching for them learning Torah privately; and they would have killed them simply because they weren’t hellinized
What’s your source?
Isn’t the simple pshat of להשכיחם מתורתך that the Greeks tried preventing Jews from learning Torah? As the Rambam writes, בְבַיִת שֵׁנִי כְּשֶׁמַּלְכֵי יָוָן גָּזְרוּ גְּזֵרוֹת עַל יִשְׂרָאֵל וּבִטְּלוּ דָּתָם וְלֹא הֵנִיחוּ אוֹתָם לַעֲסֹק בְּתוֹרָה וּבְמִצְוֹת – they didn’t allow them to learn Torah.