Is what one of the imams says true that it is desirable to recite Surat Ya-Sin and dedicate its reward to the Messenger of Allah (peace and blessings be upon him), so that its doer would be recorded among those intercessors?

We have not come across any hadith that supports what this Imam mentioned. Therefore, we advise him to fear Allah Almighty and to verify what he attributes to the Messenger of Allah, peace and blessings be upon him, for he said: "Whoever intentionally lies about me, let him take his seat in Hellfire," and he also said: "Whoever narrates a hadith from me which he deems to be a lie, then he is one of the liars." This does not include narrating a hadith with slight weakness that has an original basis supporting it, as long as it pertains to the virtues of deeds, but without asserting its attribution to him, peace and blessings be upon him, or believing in its authenticity from him. As for your duty towards this Imam, it is to advise and guide him with gentleness and wisdom.