This is not true. While some security is established by the amount of time required to get a confirmation, an attacker with a given hashrate will have a much higher probability of double spending a 1-confirmation transaction in a 10 minute block-time chain than a 10-confirmation transaction in a 1 minute block-time chain. Meni Rosenfeld showed this mathematically:
https://bitcoil.co.il/Doublespend.pdfTL;DR:
"The probability of success depends on the number of blocks, and not on the time constant T0."
These statistics are in a network latency-free statistics environment. Multiscale Monte Carlo simulations would need to be performed to find where propagation times on fast-confirmation (or huge block size) networks detectably increase the number of blocks required for the same resistance against blockchain reorganization.
This all assumes that the optimal strategy is full propagation. I fear that miners today already have incentives to prohibit propagation in order to induce the exact same conditions that happen during fast block creation.