Several points:
Of course they ignored his masonic plea; Smith had been expelled from the masons for breaking his oath, and as an expelled brother, he was not entitled to special masonic protection.
That said, the mob’s actions were wrong. I oppose mob actions of most any kind. This mob attack was certainly inappropriate. He should have been turned over to the authorities and sentenced for his crimes, just like any one else.
The temple ritual is more than just “similar” — it is identical with the exception of the added mormon theology and attacks on what-is-normally-deemed-Christianity, especially to portions of the York Rite (which used to be part of the “Blue Lodge”) down to the hand shakes and passwords. (The now-outdated “Pay Lay Ale” other “Adamaic” appears to be new, although I have not sat down and thought through any comparison.)
Regarding Mormon masons -— there are plenty. Indeed, a quick Google search will reveal many a site where mormon masons try to explore the fraternal roots of their religion.
Smith purportedly went through the Three Degrees of Blue Lodge in about one day. Since this is practically impossible, it can be argued Smith was never really a Mason in the first place.
Smith was shot in a small room in the Carthage jail after a brief gun battle in which he had killed two men and seriously wounded a third. There is no evidence anyone in the room was a Mason.
A more interesting question is whether the Mormon Temple Ceremony is Satanic?
Read these Questions for Your [Mormon] Temple Tour, and watch this reenactment of the Mormon Temple Ceremony, paying special attention to ...
Note:
Each of these terrible things is, or has been, an integral part of Mormon Temple Rites. The portrayal of pastors as satanic stooges, prayers for the overthrow of the US Government (as punishment for Mormon persecution) and the chanting of "Marvelous Lucifer" in Hebrew were eliminated a few years ago because of protests received after outsiders learned about them – despite Smith’s stern admonition that the ceremony was received directly from god and could not be changed upon penalty of death. All of the remaining practices are performed to this day.
... and then decide for yourself.