As an aside, I encounter the term "denying Gardens" quite often, but the whole concept has never made much sense to me. If something is good you want to go for it yourself; if it sucks, why bother denying it? Unless the Gardens player somehow extracts a big super-linear pay-off from having more Gardens above and beyond the super-linear pay-off you gain from investing more in your own strategy, denying seems sub-optimal. And while it's certainly better to have 8 Gardens than 5-6, I really doubt it's so much better that denying benefits you enough to compensate for the facts that
1) Gardens aren't quite free; gaining 2-3 Gardens over cards that actually accelerate your own deck presents a gigantic cost in terms of opportunity lost.
2) The Gardens will be dead cards that, once bought, almost certainly slow you down.
3) Rush strategies tend to amass a moderate amount of points quickly and then plateau. Once this plateau is reached, they seek to end the game as soon as possible, before the competing engine has burned through enough rocket fuel to reach escape velocity. Denying Gardens empties the Gardens pile faster, thus shortening the game by helping your opponent end it.
In general, "schizophrenic" strategies that do a little bit of this and a little bit of that are inferior to a strategy with focus. So unless the denial happens to align with your strategy anyway (e.g. you just want TfB fodder and don't care for the actual card) or is but a small deviation from it (which might well be the case in this particular game), I expect a strategy that wins while denying to perform even better if it does not deny at all.