Earlier quoted context omitted.
Surely Semyon would be the more common way of rendering семён?
Transliteration is almost always a mess, rarely yielding good results. If I were him I would just demand the authorities to spell my name as Simon. Or, perhaps, keep it as Semen and make fun of that myself. I could even sue someone who would ban me for this.
That only works for a very small subset of the world population. Even in the US, try sueing tictok.