I am a complete beginner and new to all of Bonsai but based off of all that I have read in books, websites and especially this forum, bonsai is like any other fad, hobby what have you, in that from person to person opinions on "whats right" or "correct" vary drastically with some core historic guidelines. I have seen pictures of bonsai species that are frowned upon as bonsai raised and trained in very stunning ways that follow bonsai rules but seem to take on the form of another tree or else cultivated and worked with the tree/shrubs natural tendencies and growth patterns with a little guidance create very stunning specimens. So to @James W. said style it to whatever looks good (or natural in this case) even if/when it ends up representing a different species. If you can have a clump or multi-trunk maple and still have it be a tree bonsai even though that's kina a shrub growth tendency then why can't you grow a beautiful azalea bonsai that grows like a shrub into a beautiful natural bonsai tree.
(sorry if none of that made sence im not good at getting my thoughts out on "paper")
(sorry if none of that made sence im not good at getting my thoughts out on "paper")