They seem to be posting a lot of word-salad comments, but assuming good faith, they're saying these are separate downsides of mutual funds over ETFs.
Mutual funds trade on your behalf, like an ETF, but they pass through the gains and losses. That can be painful if they realise those gains when you'd rather not have them, or crystallise losses when you don't have offsets. In this, they're correct. On risk, they're wrong--you can stuff nonsense into ETFs as comfortably as mutual funds. What they're indirectly criticising here is active versus passive management, which is its own can of worms.
The only advantage of a mutual fund over an ETF is it provides friction to trading. Otherwise, they're a vestige from the cusp of computerised portfolio management. (If you have more than ~$1 to 10mm, you should be rolling your own portfolio in most cases.)
