Shaykh of shias Ali Namazi ash-Shahrudi in his book “Mustadrakat ilmu Rijalu Hadith” (2/421) said:

٣٦٣٥ – الحسن بن عبد الله الارجاني:
لم يذكروه. روى عن مولانا الصادق صلوات الله عليه، وروى عنه الهيثم ابن واقد قال: من صلى في منزله ثم أتى مسجدا من مساجدهم فصلى فيه خرج بحسناتهم، كما في يب ج ٣ باب فضل المساجد ح ٧٧٨ ص ٢٧٠، ومن هذا الحديث يظهر حسن عقيدته وأنه شيعي امامي.

al-Hasan ibn Abdullah al-Irjani. WASN’T MENTIONED. Narrated from Mawlana as-Sadiq salawatullah alaihi. And narrated from him al-Haytham ibn Waqad said: Who prayed in his house then went to their (sunnis) mosque and prayed there with them, he would leave it with their good deeds…(he gives source of hadith and then Shahrudi says)……AND FROM THIS HADITH APPARENT HIS GOOD BELIEF AND THAT HE WAS SHII IMAMI.

First he said that narrator wasn’t mentioned. And that mean no one from scholar mentioned him with praise or critic.

And then he managed to make from this unknown narrator good shii fellow.

So for them it is enough to narrate something what is contradicting to unity with sunnah to become shia with correct belief!!