No, the subpoena Mr. Mueller insisted upon receiving (or he wouldn't testify) is not considered a "friendly" one according to news reports but it will be answered by the law-abiding Mr. Mueller and his legal-eagle team on July 17th, obstructions by Trump and Barr notwithstanding. Since Mr Mueller no longer works for or at the DOJ, I hope his testimony goes forward without a Trumpian hitch.
Now there is much to say about all the pertinent horoscopes involved but in the flush of this exciting morning, I haven't the time to type much of it. However, at precisely 9:00 am on July 17, 2019, Capitol Hill, royal star Regulus rises just as it does in the natal chart of Donald J. Trump although for Trump in 1946, Regulus was still @29Leo. But now the star of 'success if revenge is avoided' fame is @00Virgo, the more practical Mercury-ruled, detail-oriented sign of discrimination and purification (when expressing at its best, plus, The Critic--the one Trump is very scared of). Perhaps here I may be pardoned for remembering a previous SO'W post wondering Will Regulus Assure the Destiny of Donald Trump? for if revenge is not avoided (and who will disagree that 'revenge' is big T's middle name especially with his Mars in brash Leo rising?) all that has been gained will be taken away.
In addition, there's the harsh January 12, 2020 Great Conjunction of Saturn and Pluto @22Cap46 conjunct Trump's natal Vertex ('VX'; @22Cap51), a point of fated encounters, changing work conditions, and possible endings, a karmic event for him (and thus for America) if ever there was one. Simultaneously, transit Saturn (strong in Capricorn sign of government, law, and business) opposes Trump's natal Saturn in watery Cancer while transit Pluto aligns to do so as well. So as we know, abuse and misuse of power issues are involved in this period for Trump and his authority is challenged on a vast and permanent scale.
As for testifying Mercury the Messenger, planet of reports, reporting, reviews, and "do-overs" the little guy is retrograde which may signify the two (actually four) sessions on July 17th (a 'speaking again' for Mr. Mueller) and could also simply denote his repetition by voice of what is in his written report which he will "stick to"--and hopefully a clarification of what was misrepresented in the report by AG Bill Barr. Of course, Mercury Rx may also indicate that Mueller's July 17th testimonies won't be the end of the matter yet we don't need Astrology to tell us that! Did you say "media circus"? Well, a curious synchronicity is that Mercury @1Leo08 will conjunct the natal 12th cusp of Donald Trump and you know that the unconscious 12th house contains such realms as Politics, Large Institutions (exs: Congress, hospitals), Self-Undoing, Secret Enemies, and Karma: reaping what's been sown. But I must suppose that a straight jacket is too much to wish for even if needed.
So if we may agree, dear reader, karma is a natural law which no one escapes in the end and this must also include the likes of Donald Trump, his associates, and his family of crime.
But things get more curiouser! For testifying Mercury Rx @1Leo08 will conjunct and activate the January 21, 2019 Lunar Eclipse while opposing US POTUS Sun (00AQ+). This Lunar Eclipse was first to imprint upon year 2019 (after the January 5, 2019 Solar Eclipse @15Cap25) and you'll find some quite interesting info and astro-links in that previous post!
Also related: February 19, 2019 Full Moon Conjunct Royal Regulus making Regulus the star of the year!