I'm kinda fine listening if MCAT tells us to stay out of it. The IMO mages are planning on us showing up, as evidenced by their dedicating units specifically to neutralize us. A few things can be safely assumed:
1: whatever assets that are the "bind the Senshi" measure, are resources and manpower that could have been something else more generally useful to better assault MCAT HQ.
—Fewer units directly attacking the HQ, instead waiting for us to show up, will make things easier for MCAT on defense.
I dunno, there's always a possibility that the IMO's anti-Senshi task force exists solely to take on the Senshi and main attack force has been assembled with the expectation that they will be sufficient to defeat MCAT without further assistance. There's also no guarantee that the personnel earmarked for Senshi sealing duty might have otherwise had a place in the main attack force.
It may be the case that those mages are powerful casters, able to use all manner of spells. It's also possible that they're sealing specialists, experts in their specific field but mediocre combatants at best and expecting them to be able to significantly contribute in a battle would be like expecting a dentist to perform heart surgery.
2: The IMO is not using these assets to directly assault our HQ, but using the assault on MCAT as a way to lure us out.
—These assets are vulnerable in some way that makes using them in an attack directly against us non-viable.
I can think of a few reasons why the IMO would be wary of going after the Crystal Millennium building.
Yokai and rogue mages are known factors that the Ministry have a decent understanding of their magical capabilities. In fact, these are the exact kinds of folks that the IMO exists to 'handle.' They know what they can expect with MCAT, however the same isn't true of the Senshi.
They are after all the warriors that managed to defeat the protections used by their untouchable Empty Faces. On top of that the last time anyone on the IMO side broke into the building the Senshi, somehow, ended up with full body recordings of the perpetrators.
Who knows what other exotic magics they have in their employ and may have cast upon their home base? Trying to tie them down is going to be hard enough already, why toss in another unknown variable when an attack on more mundane target would do the job of drawing them out?
It occurs to me that if "Trust Your Allies" wins, and Samui decides she doesn't want the Senshi as part of the initial defenses, then they should still discuss what "pushing the emergency button" looks like. It probably won't be as effective as incorporating the Senshi from the get-go, but if there's at least some pre-planning to the degree of "we need back-up at Locations A and C", then there's still a better chance of snatching victory from the jaws of defeat.
Ideally Samui and co would also work out a duress code, however much that'd be worth against enemies that can manipulate people's memories.
We wouldn't want to show up expecting a battlefield only to find out that the IMO have quietly subdued MCAT with Empty Faces and faked a distress call in order to draw the Senshi to a captured base that's been remade into a ritual site.