QS is going through the amp still, so I think MaZeRaIII is trying to say is that he at least right now currently has the time stop thing. the whole no surrender is set in only time locked speed thus far.
it makes it seem like he will be able to Zen his way down from the ledge potentially coming out of I guess 'time lock'. the arc isn't over so its hard to tell what the final amp will play out to be but as right now he's gotten an astronomical amp.
QS did need the Amp from SW and SYNAPSE to get to the level but he currently still is still amped and has not found a way to slow down/undo the amp is all I think the argument was
1). That's not what he's saying. He's saying that Pietro can do so at will, when he can't:
Pietro doesn't start the forum fights in the trans-time dimension, unless he can reach it on his own. Which he can't. He also claimed it was a matter of mental block, when that was just something that Synapse removed, in order for him to access the speed amp Scarlet Witch provided him with magic, and was not the source of the speed itself. It's not. Wanda is the Source of the speed amp, and Synapse helped him properly access it.
2). Quicksilver's amp was only there when Scarlet Witch and Synapse altered him. He is no longer in that state. The problem is that, when he had the amp, he ran out of normal space/time, so he's basically in an alternate dimension now. If it makes it easier, think of you having to jump on the edge of a building, so you use a trampoline [which in the story are represented by Scarlet Witch/Synapse]. You jump on it, and you reach that edge of the building, but now you can't jump back down [you get 'stuck in time']. That's Quicksilver. He no longer has the trampoline, he can't get off the building, and he wouldn't be able to jump on the edge of the building without it.
Even furthermore, Quicksilver is not in absolute time-stop, as Scarlet Witch has been able to contact him while he is in that 'dimension', so she is able to move, slow as it is, in normal time. In fact, he even has a turtle living with him in that separate dimension - further showing that you don't need 'superspeed' to be in that state. It's a matter of being literally 'thrown' out of normal space/time [which Quicksilver did via amp, the Turtle did via Hex, and Scarlet Witch/Voodoo and Synapse do via magic]:
I see what you are saying with the 'time lock' dimension. I just understood as the amp has not played out yet to its final form. it does seem like he's using the whole emotional zen with a mixture of sw's magik to come out of dimension. the last amp bumped so much he ran into a 'between time space' dimension and now he's lost the all the amps I see it as he amped past the max and he's stuck in the dimension.
maybe its more of an altered state rather. the turtle is only animate after qs can use some magic to pull it into his state. it just reminds me of speed force like when the flash can lend a bit so they can see or act with him.