Fund rebalancing typically refers to changing the investment mix to stay within the guidelines of the mutual fund objective. For example, lets say a fund is supposed to have at least 20% in bonds. Because of a dramatic increase in stock price and decrease in bond values it finds itself with only 19.9% in bonds at the end of the trading day. The fund manager would sell sufficient equities to reduce its equity holdings and buy more bonds.
Rebalancing is not always preferential because it could cause capital gain distribution, typically once per year, without selling the fund. And really any trading within the fun could do the same.
In the case you cite the verbiage is confusing. Often times I wonder if the author knows less then the reader. It might also be a bit of a rush to get the article out, and the author did not write correctly.
I agree that the ETFs cited are suitable for short term traders. However, that is because, traditionaly, the market has increased in value over the long term. If you bet it will go down over the long term, you are almost certain to lose money.
Like you, I cannot figure out how rebalancing makes this suitable only for short term traders. If the ETFs distribute capital gains events much more frequently then once per year, that is worth mentioning, but does not provide a case for short versus long term traders.
Secondly, I don't think these funds are doing true rebalancing. They might change investments daily for the most likely profitable outcome, but that really isn't rebalancing.
It seems the author is confused.