Why would a guy screenshot my nudes and block me after I called him out?

Should I be worried about him posting them anywhere? Afterwards he asked me to send more after sending a topless pic of himself so i just left him on read now he blocked me. I don't know him in person but he still has me on Instagram and Facebook, should I block him incase does anything malicious?
Why would a guy screenshot my nudes and block me after I called him out?
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