While I do not know the details of Alhazen's reception by his contemporaries, I would point out that historians of science are extremely skeptical of anyone "laying down the groundwork for what became the scientific method." There is no single "scientific method," and the idea of using both inductive and deductive reasoning can be traced to many simultaneous advocates at many different times. Alhazen's work, as I have seen it described, sounds in line with the work of many other Abbasid scholars, who frequently combined observation and theory in their work. Nothing he is quoted as having written sounds radical for his context, at least among learned scholars and their patrons. If it is surprising as such, it is probably because most people in the West do not know much about Abbasid science.

One could ask, perhaps more usefully, whether Abbasid science and philosophy in general met with popular resistance. My understanding is that during this period, religious popular opinion could be very much opposed to philosophy (of which science was still considered a subset) in general, because it frequently involved dealing with topics considered out of bounds by a strict reading of the Koran. However the sponsorship of the caliphs for the most part (with a few exceptions; Averroes, for example, was essentially cast out by one caliph, but later rehabilitated) kept such learned scholars protected until the waning of the caliphate. And it is worth noting that during much of the Abbasid caliphate there was a relatively high degree of tolerance of other religions, beliefs, etc. (so long as everyone paid their taxes, kept the peace, etc.).

A key tenet amongst historians of science is that what we call "science" is not about some specific method so much as it is a series of social practices that took many centuries to evolve (not merely the use of observation, experiment, and theory, but institutions to support research and knowledge-generation, the circulation of knowledge, the use of reliable patronage, and the standardization of education and professionalization). It certainly owes some of its origins to Abbasid scholars, as well as many other influences. To speak of the "groundwork for what became the scientific method" sounds both teleological, as well as ahistorical — it is both a mythical understanding of what science is, and its history. (On this, general theme see, e.g., Shapin, The Scientific Revolution.)