As a general rule, the passport of entry is not even a factor.
Example of a potential exception:
A Russian/American enters Indonesia with a visa in their Russian passport and then overstays their visa. Looking to the US Embassy may not do much good.
However, a Canadian/Israeli who enters Singapore on the Canadian passport and gets done for drugs could probably ask for either/both to help.
A lot of such situations are political, so without being in the situation, we'll never know for sure.