Sua resposta está em find manpage.
A opção de exclusão é processada antes do seu filtro de nomes.
-delete
Delete files; true if removal succeeded. If the removal failed,
an error message is issued. If -delete fails, find's exit sta‐
tus will be nonzero (when it eventually exits). Use of -delete
automatically turns on the -depth option.
Warnings: Don't forget that the find command line is evaluated
as an expression, so putting -delete first will make find try to
delete everything below the starting points you specified. When
testing a find command line that you later intend to use with
-delete, you should explicitly specify -depth in order to avoid
later surprises. Because -delete implies -depth, you cannot
usefully use -prune and -delete together.
Você poderia ter movido a opção de exclusão como a última do seu comando
Alternativamente, você poderia ter usado algo como
find /path -name "*pattern*" | xargs rm -f
ou
find /path -name "*pattern*" -exec rm -f {} \;