If the author's setup can only statistically determine effects of 30% or higher, saying "there's no significant change" means "there's no significant change of 30% or more".

Nothing can be said of changes of less than 30%, and that's a hell of a lot of uncertainty. One of the variants could give you 25% more results and yet, those experiments would not see such a result.

As such, it is clear that the experiment is simply not thorough enough to imply the two alternatives are equivalent. Not in the least.