Security patches are the last place (especially tiny ones) where you want to make a stand for proper attribution of four line patches, the rest got properly credited. Note that the OP misrepresented the nature of the exchange with the kernel maintainer and that puts their motivation about the whole thing in doubt. Nobody got robbed. OP still has contributed code, the LKML lists are proof of that and if you think that in the future every such patch should carry an automatic 'Suggested-by' or 'Coauthored-by' tag then you could propose that. But for now this is the maintainers call and by sending mail to the LKML you play by their rules.

That's not gatekeeping, that's just reality, and yes, kernel maintainers are an in-group whether we like it or not. My take on that is that if I had stuff that gets included that I couldn't care less about the attribution because what they give me is so much more than I'll ever be able to give back. Of course everybody is welcome to their own motivations, but you send unsolicited patches with the hope that they'll be used, if you get credit that's great but then the patch had better be ready to run as is and preferably for something a bit more substantial.