Yeah you are right if one don't call Bitcoin by it's name you may mislead some newbies, I know someone who believed that all other crypto coin are also known as Bitcoin which lead him to invest in a shitcoin and he lost his money, so we should always call Bitcoin by it's name to avoid complicating things.
Ponzi scheme has really made a lot of people lose there money and by the mention of the name Ponzi what comes to some people's mind is scam and Bitcoin should not be link to Ponzi as is a very different thing.
People should understand that there are newbies who don't engage in discussion here but often come on threads like this to learn about Bitcoin investment therefore everyone has to be careful concerning things they say so as not to mislead those newbies and give wrong impression to them about Bitcoin, he might not have called Bitcoin a Ponzi but relating it to that name alone is mislead and once those newbies learn that a high ranking member is relating Bitcoin to Ponzi then they'll think it has scam features on the long run, let's the guided and try as much as possible possible to pass the right informations while we discuss about the concept of Bitcoin investment, Bitcoin has nothing relating to Ponzi and if one invest on Bitcoin the right way and follow it concepts thereby using good methods then they'll benefit from it and even recover loses, expect for those who use it for trading despite being aware of the high risk factor.
For other people who have lots of experience to deal with bitcoin provably they would know the point of those tricky opinions. But we should not forget that there are so many newbies that can able to read each sentences we write. That's why its really good for us to avoid writing up any possible statement that can mislead people.
That's why I agree to those people saying that we should call bitcoin as on its name and separate that crypto calling to alts. For calling a name which is related to scam then provably it will confuse newbies and worst they might think that its a scam because someone call it as Ponzi.