[acqq]

You are right. Here is the source of "compress" that existed at that time. It compresses the produced song to 1048 bytes, not less.

https://www.nic.funet.fi/index/minix/compress.c

The program that produces the song, without the introductory comment, is 913 bytes, as presented in the article. Removing whitespaces it uses just 800 bytes and produces the song which is 2359 chars here. The whole C is:

    main(t,_,a)char*a;{return!0<t?t<3?main(-79,-13,a+main(-87,1-_,
    main(-86,0,a+1)+a)):1,t<_?main(t+1,_,a):3,main(-94,-27+t,a)&&t==
    2?_<13?main(2,_+1,"%s%d%d\n"):9:16:t<0?t<-72?main(_,t,
    "@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l,+,/n{n+,/+#n+,/#;\
    #q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/+k#;\
    q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){nl]!/n{n#'; \
    r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#\
    \
    n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c ;;\
    {nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;\
    #'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/")
    :t<-50?_==*a?putchar(31[a]):main(-65,_,a+1):main((*a=='/')+t,_,a+1):
    0<t?main(2,2,"%s"):*a=='/'||main(0,main(-61,*a,
    "!ek;dc i@bK'(q)-[w]*%n+r3#l,{}:\nuwloca-O;m .vpbks,fxntdCeghiry"),a+1);}

It compiles and links even without #include.