Well, if Tager barriers the groudn pressure, if he wants to keep that momentum, he's going to have to gamble on that rising j.b and badly spaced that can trade with 2c, which we all know what goes into. That's one reason I believe you don't see a lot of:
6a 5a > 2a 2a > 5a
used in strings. Barrier blocking compromises the spacing needed for rising j.b to be valid pressure, or anything else really. And since 6a is apparently slower, we need to make people scared to mash out of stuff, and that's why it's used sparingly and with proper conditioning. 2 interesting things about Arakune's 6a is that it's not only air unblockable, but gatlings into his new 6b as well, so that's an option in case Tager wants to jump out/A Sledge/360/720 through anything after 6a.
6a is probably still even on block, and his new 6b is no slower than 8f start up (probably still 6), that's air tight.