The price (and therefore value?) of satoshis rise/fall at the exact same rate as a price of a bitcoin, so I don't see how this invalidates their argument.
if you can acquire 0.0006USD worth of bitcoin then the price of bitcoin alone is not a limiting factor. Maybe if OP is talking about hundreds of years in the future and BTC is worth $1 Million+?
If the USD were completely replaced with bitcoin (ignoring long transaction times and other garbage) you'd expect approximately 1BTC for every $1.3M currently in circulation. In just a few decades even a Satoshi would be worth the equivalent of $1+.
while I don't really agree with the bitcoin maxi mindset of the comment you are replying to, do you know that you can buy as little as 1 satoshi? (0.00000001 BTC). Yes, eventually all BTC will be mined (in about 2140) but considering 1 sat is currently worth 0.0006 USD, there is still quite a bit of room for very small amounts of bitcoin being widely accessible (fees being a different issue that will improve with time).