They are illustrating the author's contention that Stallman's rhetorical approach is similar (and similarly offputting to anyone not already committed to the cause) to that of the LaRouche crowd, and are presented in pairs with a LaRouche poster beside one from the FSF/Stallman side (the Windows 7 sins is from the FSF, I'm not sure of the origin of the "Swindle" poster but the "Swindle"-as-abusive-alternate-name-for-Kindle thing is something that, per the letter writer, Stallman engaged in in the speech.)
In my opinion, including a picture of Obama as Hitler (which has nothing to do with any Stallman/FSF statement) raises an already tenuous ad hominem attack to its Godwin extreme. That they aren't clearly labeled is disingenuous at best.
Its not an ad hominem attack. Saying Stallman's arguments are wrong (or, in a weaker form, that they should be dismissed) because of the tactics similar to those of the LaRouche crowd similarity would be ad hominem.
Saying that Stallman's presentation of his ideas is, in fact, alienating to people who aren't already converts, and that the presentation's similarity to LaRouche extremists tactics is helpful in understanding why that happens (whether or not it should happen) is tactical criticism.
There may be a problem with it, but it isn't even remotely ad hominem.
