Professing the Baha'i Faith myself, I've actually spoken to a number of Baha'is from Iran, and have heard stories of how Muslims can be affected by this oppression too.
For instance, what many forget is that while it is common for Baha'is in Iran to be raised and educated by Baha'i parents, many do not have Baha'i parents. In many cases, their parents are Muslim. There are also cases of Iranians becoming Baha'i after marriage.
In both of these cases, it is common for these Muslim parents and spouses to attract suspicion from the authorities or face questioning of their parenting etc.
And needless to say that in Iran, just attracting suspicion from the authorities is nerve-racking enough.
There have also been cases of Muslims facing harassement for standing up for Baha'is, and I've never heard of a Baha'i blaming Islam for this oppression. In fact, Baha'is believe in the Qur'an and Ahadith, and generally lament the lack of Fath in Iran (not to be confused with fanaticism) than the presence of Islam itself.
This makes it ironic that opponents of Islam should insist of using the oppression of Baha'is as a cheap shot against Irlam when Baha'is themselves do not blame Islam for their oppression.