I'm breaking my answer down into two sub-answers:
- Why the passage in Rev. isn't that weighty
- How the Bible speaks about the persons within the Trinity
Rev. 14: An argument from silence
If the thesis is that we shouldn't worship the Holy Spirit since he isn't specifically mentioned in Rev. 14:1, then, (as with all arguments from silence) the burden of proof is on them to find passages within the Bible that demand worshipping only two persons instead of three.
Also, Revelation is the last place to start when it comes to matters like this, since it's so replete with visual and figurative language.
It should not shock or surprise us that the Holy Spirit is not mentioned here, since there are many other places in the Bible where the Father and Son are mentioned but the Spirit is not. Here's a brief sampling:
- 1Pet. 1:1
- 2Pet. 1:2
- 2John 3
- Rom. 1:7
It gets a little embarrassing to list all these passages since they appear so frequently throughout scripture.
Even though the burden of proof lies on those who deny the Trinity here, it should not shock us to see the absence of the Holy Spirit specifically, since the Holy Spirit is most content to shine the spotlight on Jesus and his work. In that sense, emphasizing Jesus and his salvific work is the best way to emphasize the Holy Spirit.
How does the Holy Spirit reveal the persons within the Trinity?
Two persons, not just one: There are numerous places in the Bible where two persons are mentioned and not all three. it's absolutely absurd to conclude that when these two persons are emphasized in context that only those two exist. Examples:
- Father and Son.: Gn 19:24; Ps 2:2,7; 45:6,7; 110:1; Jr 23:5,6; Ho 1:7; Mic 5:2.
- Father and Spirit.: Is 63:10,14
- Son and Spirit.: Zch 12:10
- Lord (God) and Spirit.: Nu 11:25,29; 1 Sam 10:6; Is 44:1–3; Jl 2:28;—Nu 24:2; Job 33:4; Ps 51:11.
Equality and personality of the Holy Spirit affirmed in scripture:
a) Personality.
He is not an abstract power or influence emanating from God.
1) He is coordinated with the Father and Son.
cf Mt 28:19; 2 Cor 13:14;—Mt 12:31,32; Jn 14:16,26; 15:26 coll 1 Jn 2:1.
2) Personal activities are ascribed to Him.
cf Ro 8:27; 1 Cor 12:11.
cf Mt 1:18; 4:1; 10:20; Lk 4:18; 12:12; Jn 14:26; 15:26; 16:7,8,13; Ac 8:29; 20:28; Ro 8:26; 1 Cor 2:10; 3:16; 1 Jn 5:6; Re 2:7.
cf Ac 5:3; 7:51; Ro 15:30; Eph 4:30; Is 63:10.
b) Divinity.
By ascribing to Him
1) Divine names.
cf Ac 5:3,4; 28:25 coll Is 6:8; 1 Cor 3:16; 2 Sam 23:2,3.
2) Divine attributes.
cf Ps 139:7;—1 Cor 1:10,11;—He 9:14.
3) Divine works.
-a) Creation.
cf Gn 1:2; Job 33:4; Ps 33:6; 104:30.
-b) Redemption.
cf Mt 3:16; 4:1; Lk 1:35; 4:18; He 9:14; 1 Pe 3:18 (?).
cf 2 Cor 13:4; 1 Tim 3:16.
-c) Directing God's ministers.
cf Ne 9:30; Zch 7:12; Mt 10:20; Jn 15:26,27; 20:22,23; Ac 2:4; 13:2–4; 20:28; 1 Pe 1:11,12.
-d) Administration of the Church.
cf Jn 3:5; Ac 15:28; 1 Cor 3:16; 12:1–11; Eph 2:22; 4:3,4.
4) Divine honor.
Coordinating Him with the Father and the Son.