As you can see diversifying crypto portfolio for them means investing in deferent crypto assets which are much wider than just a bitcoin.
But let's take a look at the returns on those coins, in terms of BTC:
EOS - down 95% from peak
NEO - down 95% from peak
XLM - down 90% from peak
OMG - down 95% from peak
XRP - down 95% from peak
BCH - down 95% from peak
ARK - down 97% from peak
ZEC - down 98% from peak
Now, we obviously don't know exactly how much of each coin they are holding or when exactly they bought it, but in almost all scenarios buying these coins lost them money compared to buying bitcoin alone and did not reduce the risk of their portfolio compared to buying bitcoin alone. If bitcoin crashes, these altcoins will all crash even more too.