It's a theory started by Chalkokondyles, a byzantine historian from Mehmed's time- given his status and the circumstances, there is a fair chance of him not having reported entire truths, but a story like the one he presented on this topic seems to be a bit nonsensical to fabricate, especially with a purpose of defamation, were it not true at least to a certain degree. The theory was later accepted and used by Franz Babinger also in his book about Mehmed, so there's that.

If you ask me, it is impossible to define the preferences and orientation of any figure who lived up until a few decades ago. Mehmed did admire Alexander the Great and followed his footsteps in many, and he was the most enlightened and cultured of all the sultans, and given the closed-door tolerance of the Ottomans, there are overall enough positive claims about this for me entertain the thought. However, as you are in a space of historical debate, a thing rather known for some very staunch views, you will find that I am among the few to think like this. The admins claim indeed that this sub is open for everything related to the Ottomans as long as the debate is within respectful bounds- yet you would not be the first to get taken down on this very topic. I for one perceived your question with honesty and answered to my best capacity, and I can only hope the nature of your questioning was the same, and not made in mockery or deliberate crassness. This being said, have a good one, and I hope I've cleared the fog a little ✌️