Bitcoin Strategic Reserve vs Altcoin StockPile Difference:

First)

 Bitcoin will never be sold in the future
Altcoins can be sold if needed

Second) 

More Bitcoin can be bought in the future, except through money printing and using taxpayers' money. 

For example -> Sell gold for Bitcoin, Issue Bitcoin Bond on existing Bitcoin, use idle cash of the various departments in the US government.

No more Altcoin Buy in the future.

Third)

Bitcoin is now officially a strategic asset.
Altcoins are not, they are part of the digital asset stockpile.