To be fair, I wouldn't call that "dumping" but "delegating". To me, it is just the same as Erwin asking Armin for a plan regarding Reiner and Berdholdt lurking around: if the person in charge believes they aren't qualified for the situation at hand, it is much better to delegate that role to somebody else, even if it is on minute notice.
If Armin didn't make that decision and was lost in thought for any longer, it could cost the life of Eren and everyone else.
Armin is good when it comes to thinking outside the box and long term strategy, but Jean is better when it comes to urgent assessment and short term tactics. Both are aware of their respective strong points and weaknesses, hence why Jean took the lead, but warned Armin the latter is still needed in the grand scheme of things.
By the way, due to leaks,
Funimation (and most likely other simucast companies) is forced to delay the release of the simulcast, to prevent any possible incident prior broadcast in Japan.
As such, subbed episodes are to be released on Wednesday instead of Sunday. This measure is immediately in application, so Episode 54 will be subbed on Wed 29th May, instead of Sunday 26th.