I think that is an issue for personal security not the Bitcoin Transaction Security itself. No one can hijack anyone transaction happened on blockchain and the probability of a private to be hacked if its not used on untrusted website is very slim. I mean the reason why people hacked is because they let the hacker hacked them. But technically speaking about blockchain, it's very hard to hack a transaction because its peer to peer.
True. But there's a significant difference between "Bitcoin transactions are secure and irreversible" and "there is no chance of losing money". If what you said was what OP was trying to say, then it definitely could've been worded a lot better. Such statements can be really dangerous.
Fair enough. His though was too generalised that's why it creates too much open room for discussion.
They removed bitcoin due to price volatility and irreversible function which is against there ToS. Bitcoin is not removed just because it is not secure and so on. I believe this is the reason why stablecoin are more appropriate to used as payment instead of BTC on this kind of services.