A better question might be "Is Homo Economicus a Strawman?" To which the answer is: yes, it is. Classical economics does not actually assert that individual humans behave in a purely rational and fully-informed manner. A more accurate premise is that groups of humans tend on average to act at least somewhat as if they were rationally well-informed. We have tools to determine what "rational" behavior might look like a…
That's a wigglier definition of "rational actor" than neoclassical economics actually admits.
More precisely, neoclassical economics posits that economic equilibriums are the same as they would be if humans were rational actors. Random irrationality doesn't affect the equilibrium, but systematic irrationality certainly does.
Showing that people are systematically irrational about many things, as for example the work of behavioral economists does, certainly is not an unjustified attack on neoclassical economics.